Repurpose a YouTube Video into Shorts and Reels with a Claude Skill (Clip Finder + ffmpeg Commands)

One good long video can feed your Shorts, Reels and TikTok for a week. The hard part is not the cutting, it is finding the moments that work on their own and giving each one a hook strong enough for a feed where viewers decide in about a second. This guide gives you a free Claude Skill, shorts-repurposer, that reads a timestamped transcript, picks the best 15-60 second moments, and writes the hook, title, caption and on-screen text for each clip. It also outputs ffmpeg commands that cut and crop each clip to vertical 1080×1920, which I tested before publishing. You also get the current length limits for each platform and the originality rules that decide whether repurposed clips get reach.

Why repurposing works (and when it does not)

Short-form feeds reach people who would never click a 15-minute video. A good clip introduces them to you, and some will come back for the long version. Because the clip comes from content you already researched and recorded, the extra effort is small.

It does not work when the clip depends on context (“as I said earlier…”), when it starts slowly, or when it is just a random 30 seconds of the video. That is why the skill looks for self-contained moments and rewrites the first line if needed.

Shorts, Reels and TikTok specs compared

Practical sweet spot for clips: 20-45 seconds. Long enough to deliver one idea, short enough to keep most viewers to the end.

Step 1: get a timestamped transcript

• From YouTube Studio: Content > your video > Subtitles > the language row > Options (three dots) > Download, and choose .srt or .vtt. Auto-generated captions work fine for finding moments.
• Before uploading: use a transcription tool. Local Whisper-family models create SRT files on your own PC for free. Many editors (DaVinci Resolve Studio, Premiere Pro, CapCut) also create captions.
• In Claude: attach the .srt or paste it. For long videos, an SRT is better than plain text because every line has a time.

Step 2: the shorts-repurposer skill

Save the file as shorts-repurposer/SKILL.md. On claude.ai, zip the folder and upload it under Customize > Skills (code execution must be on in Settings > Capabilities). In Claude Code, copy it to ~/.claude/skills/shorts-repurposer/. The Claude Skills guide explains the format in detail.

---
name: shorts-repurposer
description: Finds the best 15-60 second moments in a long video transcript and turns each into a vertical Short, Reel or TikTok package (cut times, hook, captions, title, on-screen text) with optional ffmpeg commands. Use when the user wants to turn a YouTube video or podcast into Shorts, Reels or TikToks, or asks for clip ideas from a transcript.
---

# Shorts repurposer

## Input
A transcript with timestamps (YouTube Studio > Subtitles, or any transcription tool). If it has no timestamps, ask for one, because cut points depend on them.

## Steps
1. Read the whole transcript. Find 3-8 moments that work alone, without the rest of the video: a surprising fact, a quick how-to, a strong opinion, a before/after, a funny or emotional beat.
2. For each clip give:
   - Start and end time (15-60 seconds; YouTube Shorts can run up to 3 minutes, but most clips perform better short)
   - Hook: the first line on screen and spoken. If the clip's first sentence is weak, suggest a new 2-3 second opening line to record or add as text.
   - Title (under 40 characters is safest for the Shorts feed)
   - Caption for Reels/TikTok (1-2 lines + 3 hashtags)
   - On-screen text beats
   - Why it works, in one line
3. Rank the clips by expected strength and say which 2 to post first.
4. If the user has the video file and ffmpeg, give one command per clip to cut it to 9:16:
   `ffmpeg -ss START -to END -i input.mp4 -vf "crop=ih*9/16:ih,scale=1080:1920" -c:v libx264 -crf 20 -c:a aac clipN.mp4`
   This centre-crops a 16:9 video. If the speaker is off-centre, tell the user to adjust the crop x offset or reframe in an editor.

## Rules
- Only clip videos the user owns or has rights to. Clipping other creators, TV or sports without permission is reused content on YouTube and unoriginal content on Facebook.
- Each clip needs a hook in the first 2 seconds and must make sense without the long video.
- Keep captions accurate to what is said; no clickbait the clip does not deliver.

⬇ Download SKILL.md Save it inside a folder named shorts-repurposer

Ask: “Find Shorts in this transcript” and attach the SRT. In Claude Code you can point it at a folder: “/shorts-repurposer transcripts/ollama-video.srt, video file is raw/ollama.mp4”.

Example clip plan

The skill’s output for a long tutorial on running local AI looks like this (two of six clips shown):

Plus a caption for Reels/TikTok, like: “Your GPU isn’t broken. Try these two fixes first. #localai #ollama #pcbuild”.

Step 3: cut clips with ffmpeg

ffmpeg is a free command-line video tool (Windows: install with winget install Gyan.FFmpeg; Mac: brew install ffmpeg; Linux: your package manager). These are the commands the skill writes. I ran each one on a 1920×1080 test video and checked the output is 1080×1920 at the right length.

Centre crop to vertical

ffmpeg -ss 00:04:31 -to 00:05:08 -i input.mp4 -vf "crop=ih*9/16:ih,scale=1080:1920" -c:v libx264 -crf 20 -c:a aac clip1.mp4

Speaker off-centre: shift the crop

The crop filter is crop=width:height:x:y. To move the window 200 px to the right of centre:

ffmpeg -ss 00:07:20 -to 00:07:55 -i input.mp4 -vf "crop=ih*9/16:ih:(iw-ih*9/16)/2+200:0,scale=1080:1920" -c:v libx264 -crf 20 -c:a aac clip2.mp4

Use a negative number to move left. If the important thing moves around the frame, reframe in an editor instead.

Burn in captions

Ask Claude to cut the SRT down to the clip and shift its times so the clip starts at 0, then:

ffmpeg -i clip1.mp4 -vf "subtitles=clip1.srt:force_style='Fontsize=18,Alignment=2,MarginV=60'" -c:a copy clip1_captioned.mp4

Captions matter because many people watch short videos with the sound off. On Windows, run the command from the folder that holds the SRT, because drive-letter paths inside the subtitles filter need extra escaping.

Batch all clips

In Claude Code, ask the skill to write a small script (cut_clips.sh or cut_clips.ps1) with one line per clip and run it. Check the first clip before running the rest.

No command line? Use an editor

The skill still helps with these tools: use its time codes and hooks as your edit list, so you are not scrubbing through the whole video.

Step 4: post without hurting reach

• Export clean files. Post the original export on each platform, not a download from another app. Watermarks from other platforms can reduce distribution.
• One clip per day per platform is a sustainable pace and lets you see which hook types work.
• Link back. On YouTube, link the Short to the full video using the related video option. On Reels and TikTok, mention the full video in the caption or pinned comment.
• Write a new first line when the original sentence is weak; the first two seconds decide everything.
• Stay original. YouTube’s reused content policy and Meta’s unoriginal content update both target clips of other people’s content without meaningful additions. Your own videos are safe; other creators’, TV, sports and film clips are not, unless you add substantial commentary and have the rights.

25 Shorts ideas from one long video

Troubleshooting

FAQ

How many Shorts should I cut from one video?

Usually three to eight. Only clip moments that stand on their own. Five strong clips beat fifteen weak ones.

Can I repurpose the same clip on YouTube, Instagram, Facebook and TikTok?

Yes, if it is your own content. Upload the clean original file to each platform rather than re-downloading from another app with its watermark.

Can Claude cut the video itself?

In Claude Code, yes: with ffmpeg installed, Claude can run the commands on your files. On claude.ai, Claude plans the clips and writes the commands, and you run them on your computer (large video files are not practical to upload to a chat).

Do Shorts views help my long videos?

They can bring new subscribers and some click through to the long video, especially when you link it. Shorts views also count toward YouTube’s 10 million Shorts views path into the Partner Program, but Shorts watch time does not count toward the 4,000 watch hours.

Is it allowed to clip other creators’ videos?

Only with permission and meaningful additions. Clips of other people’s content without substantial commentary are reused content under YouTube’s monetisation rules and unoriginal content under Meta’s.

What is the best length for a Short?

There is no single best length. Many creators find 20-45 seconds works well for one idea. Watch your own retention: if most people leave before the end, cut the clip shorter.

Final Thoughts

Repurposing is the highest-leverage habit for any video creator: the research and recording are already done. The skill turns a transcript into an edit list with hooks in a minute, and the ffmpeg commands handle the cutting. Use your saved time on better first lines and clean captions. For the rest of the pipeline, see the Claude Skills for YouTube pillar, the script writer skill and the Facebook page planner.

Sources

• YouTube Help: Understand three-minute YouTube Shorts
• YouTube Help: YouTube Partner Program eligibility
• YouTube Help: Reused content policy
• Reap: Video length limits for Shorts, Reels and TikTok (Aug 2026)
• TechCrunch: Meta crackdown on unoriginal content
• FFmpeg filters documentation