If a video doesn't generate automatic captions, it could be due to one or more of the following reasons:
- The captions aren't available yet due to processing complex audio in the video.
- Automatic captions don't support the language in the video.
- The video is too long.
- The video has poor sound quality or YouTube doesn't recognize the speech.
- There is a long period of silence at the beginning of the video.
- There are multiple speakers whose speech overlaps.