Before downloading a shortcut to convert my screen recordings to GIF format for my last bug report, I tried uploading the original videos directly. Rather than getting an error for what I assume is video uploads not being supported, or perhaps the 10.5MB video being too large, I received the following error message:

Not sure if it's a glitch, or just an unclear error message, but I'd thought I'd try to be as descriptive as possible.

Edit: The issue has since also occurred with a 7.2MB, 33 second GIF. If it helps narrow down the cause, the issue did not occur when I uploaded a 23 second re-recorded version of the video that ended up being 5.7MB after converted into GIF format.