Hello all! There is an issue causing video uploads to Flickr to fail right now. The Flickr Team is aware of the problems and are working on it right now! We do not have an estimate on when this will be resolved, but will let you know as soon as we have that. Meanwhile, you can keep en eye on this Help Forum topic in the meantime. Sorry for the inconvenience!
Update 11:20AM PST: This issue has been resolved, so feel free to upload your video!