I get that every time I try to upload dTube.
I've figured out that if I log out and back in that seems to fix it.
Also the special characters thing makes sense too.
I've only ever had a dtube succeed after taking and uploading snap while it's uploading don't cut and paste, I can tag while it uploads but can't move it over to the advanced tab or the subtitles tab.
Using Opera Browser it has more functionality as well.