Long to Short Video
One long video → 5–10 standalone shorts. Each clip must make sense with no context from the long video.
Before you cut
Ask for (or confirm) in one short question if missing:
- The long video file or link, and its length / topic
- How many clips? Default: 5
- Target platforms? Default: Shorts + Reels + TikTok. Add LinkedIn / X / Bilibili only if asked — they need different cuts (see below).
- Language of captions? Default: the video's language.
The rules of a good clip
- One idea per clip. If it needs "as I said earlier", it's not a clip.
- Hook in the first 2 seconds. A question, a bold claim, or a result — not "hi, welcome back".
- Length: 30–60 seconds is the sweet spot, 90 seconds max for a universal clip. Hard ceilings (checked Oct–Nov 2026): YouTube Shorts ≤3 min, Instagram Reels recommended ≤3 min to new audiences, TikTok up to 60 min uploaded but clips should stay short, X free ≤2 min 20 s, LinkedIn ≤15 min but 30–120 s performs best, Bilibili vertical clips 3–15 min sweet spot.
- Start and end clean. Cut on a complete sentence. End with a payoff, a CTA, or a loop back to the hook — never mid-word.
- Captions burned in. Most people watch muted. Big, high-contrast, centred, 2–3 words per line, inside the safe zone (keep text away from the top 15% and bottom 20% — that's where platform UI sits).
- Vertical first. Master export: 9:16, 1080×1920, H.264 MP4 + AAC, 30 fps. Crop the speaker to centre; don't just shrink a 16:9 frame with black bars.
Steps
- Find moments. From the transcript / chapters / timestamps, list candidate moments with start–end times and a 1-line reason each. Rank them: strongest hook first. Pick the top 5 (or the number asked for).
- Write the clip plan using
templates/clip-plan.md: for each clip — title, hook (first line spoken), start–end, why it works standalone, caption text, hashtags per platform. - Cut. Use
scripts/make-clips.sh(ffmpeg) with aclips.csv— see the script for the format. It crops to 9:16, scales to 1080×1920, and normalises loudness to −14 LUFS. Verify each output: correct length, audio present, speaker centred, no black bars. - Caption + title each clip. Title ≤100 chars for YouTube, ≤80 chars for Bilibili, ≤280 chars total post for X. One CTA per clip, same link everywhere.
- Platform cuts. One master clip does not fit everywhere:
- Shorts / Reels / TikTok / Facebook: the master 9:16 clip, ≤90 s.
- X (free): cut to ≤2:20, H.264, ≤512 MB.
- LinkedIn: 30–120 s, 4:5 (1080×1350) or 9:16, professional hook — cut the joke, keep the lesson.
- Bilibili: vertical 9:16 works, but add a Chinese title + tags if the audience is Chinese, and a cover frame.
- Show the plan before cutting. The user approves the moments + hooks first. Cutting is the expensive part — don't cut 10 clips to find out they wanted 3.
Clip plan template
## Clip 1 — "The 2-minute invoice trick"
- Source: 12:04–12:58 (54 s)
- Hook (first 2 s): "You are losing $400 a month to late invoices."
- Why standalone: complete tip, no setup needed
- Caption: …
- Platforms: Shorts, Reels, TikTok, X (54 s, fits free X)
Don't
- Don't generate video, and don't claim to. This skill plans and cuts from a video the user provides.
- Don't cut a clip that only makes sense inside the long video.
- Don't burn in captions that cover the speaker's face.
- Don't upscale a 720p source to 1080p and call it HD — note the source quality.
- Don't post the clips yourself. Hand over the files + the post pack (use the
social-media-postingskill for captions per platform). - Don't use copyrighted music from one platform's library on another platform — a Short with a claimed song can be blocked.