Because of its shape. YouTube makes a video a Short only when it is vertical or square. A wide 16:9 video is a normal video, and there is no setting that can force it to be a Short.
How YouTube decides
- There is no "post as a Short" switch. Not in the app, not for apps like sprkly.
- YouTube looks at the shape.
- As tall as it is wide, or taller: it can be a Short.
- Wider than it is tall: it is a normal video.
How to fix it
- Re-export the video vertical, 9:16. 1080 x 1920 is a good size.
- Keep it 3 minutes or shorter.
- Upload it as a new post. A video that went out wide stays a normal video.
Other YouTube rules in sprkly
- A title is required, 100 characters or fewer.
- The description can hold up to 5,000 characters.
- YouTube is video only. There are no photo posts.
- A Short takes no separate cover. If you pick a cover, sprkly bakes it in as the first frame.
Before you schedule
- Compose has a shape guide for each platform.
- For a wide video, it marks YouTube "Not a Short".
- When a video does not match the shape you picked, Compose opens a crop tool.
- You frame the crop yourself. Cancel keeps the original.
Posting the same clip to Reels and TikTok?
- A 9:16 video works on all three.
- So one vertical export covers Shorts, Reels and TikTok.
Do it in sprkly: In Compose, choose 9:16, upload your video, and frame the crop when it opens. YouTube then gets a vertical video it can treat as a Short.
Docs: sprkly docs