@Go Foxi23 This issue was fixed yesterday. We've also improved the UX a little bit. Now, when a user uploads MP4 or WebM videos, we display the unprocessed video right away and start the processing in the background.
For other video formats, like Mov, we still need to show a "Processing note" placeholder while processing the video in the background. Unfortunately, this is web browsers limitation and we cannot improve it further.
For the previous videos that failed you will need to remove and reupload them. Please let us know if we can help in any way.