I tried uploading a new video 3 times.
One time it logged out (which happens from time to time; Not the best timing at upload but ah well)
Both other times I received: Possible file upload attack. Filename: XXX
There is a next button, after pressing this: The selected file does not exist, or for some reason is unreadable.
Solution : clean the filename from any symbols such as ' " % $ é ....
If the problem persists, please contact the webmaster.