Error #40 reuploading a document I've already published.

A month or two ago, I published a relatively small digital document that contained a video with no problems.

Today, I had to make a couple small text edits. I went to reupload the file but started getting an Error #40. No changes had been made to the video.

The vdieo is definitely the source of the error (I reuploaded without the video and had no issues).

What could be causing the issue now that wasn't an issue at the time of the first upload?