The file transfers unchanged. What most people get wrong is treating the YouTube description as a caption, when it’s doing an entirely different job.
Feed versus search
Instagram is a feed. A Reel gets its views mostly in the days after posting, and the caption speaks to someone already looking at the video.
YouTube is a search engine. A Short can keep accumulating views months later, found by people searching for the thing it’s about. The description and title are a large part of how that happens.
So the same 30-second video has a short lifespan on one platform and a long one on the other, and the text is what makes the difference.
| Instagram Reel | YouTube Short | |
|---|---|---|
| Caption limit | 2,200 | 5,000 |
| Max video | 1 GB | 128 GB |
| Formats | MP4, MOV | MP4, MOV, AVI, FLV, WebM |
Write the YouTube description properly
The two-word caption that works on Instagram wastes the Short.
A description worth writing has a real sentence or two saying what the video shows, in the words someone would actually search for. Then whatever links or context belong underneath.
This is the single highest-return difference between a cross-posted Short and a native one, and it costs a minute.
Don’t download from Instagram
The usual rule: keep your original export and upload that file to both. A Reel downloaded from Instagram carries a watermark and has been recompressed. On YouTube, where the video may be found by strangers months later, arriving with a competitor’s watermark is a worse look than it is in a feed.
Check the on-screen text
Instagram’s interface elements sit differently from YouTube’s. Text positioned to clear one may be covered on the other. Worth checking once with a real post before queueing a batch.
The workflow
- Export the clean vertical video from your editor
- Upload it once
- Select Instagram and YouTube
- Write the Reel caption, then write a real YouTube description rather than reusing it
- Pick a time and queue it
Media rules are validated per platform before the post is queued, so a file over Instagram’s 1 GB ceiling is flagged while composing.
Add TikTok
The same file works there too. TikTok, Reels and Shorts is the standard vertical trio, and going from two platforms to three is one more caption rather than another upload.
Plan limits
BulkPublish publishes to Instagram, YouTube and 13 other networks.
- Channels: Free: 3 (1 per platform). Pro: 30 (2 per platform). Business: 75 (5 per platform).
- Posts: Free: 3/day. Pro: 30/day. Business: unlimited.
- Storage: Free: 100 MB. Pro: 2 GB. Business: 10 GB.
Storage is the constraint for regular video posting, not channel count.
The short version
Upload your original export to both rather than downloading from Instagram. Then write the YouTube description as search text rather than reusing the caption, because a Short can be found months later and the description is how. That one minute is most of the value in this cross-post.