Are you uploading via Google Chrome? That has worked for me when I upload and previously I uploaded the hour long Tapestry of Terror vid and it worked fine. The upload was relatively fast then, compared to You Tube uploading time.
On a related note, I have had a problem with my archive disappearing posts from my main DTube channel page. I have uploaded over 45 videos but right now my channel archive shows only 15 videos there. The rest are showing deep down on my Steemit stream but not in the main Dtube channel archive itself.
Thus, a few glitches going on. You can also present you question to @heimindanger
Found an older thread on large file size uploads here:
https://steemit.com/video/@surfyogi/dtube-file-size-limits-my-large-file-failed-to-upload-at-638mb