"The server has rejected the file. Please [follow these steps] and upload the file again."
Damn it, @TeamYouTube , stop mucking about. The file is good, the browser is good, its all good. Everything is the same, and yet YOU have the problem. WTH?
I'm uploading 5, 30-min vids. Started off with this error, but uploaded the same file and it passed. Got to the 3rd., and got the error, but now it goes. Nothing changed on my end.