The maximum amount of imported video is the length of the video divided by 2
For example, if the video is 1 hour long, it will take 30 min to process.
the minimum amount will be 5 minutes.
Reach out to support if takes longer than that
If it was imported from YouTube or Vimeo, the import API could be down and if it wasn't upload then it could be a corrupted video or non-standard encoding.
Please make sure your video has clear audio, if audio is missing/unclear this will cause an issue in processing.