These are all worth a try and possible fixes. The account I'm using now is new and haven't been able to solve my problem. My other account (ramosxp) that's a few weeks old I was able to upload several videos after initially getting the error.

What I did for that fix was re-edit the video , not just upload the video I downloaded from Youtube. I'm going to try that again on the new account. If it doesn't work, I'll try uploading a different time of the day.
I've tried different browsers, chrome, firefox, safari, seamonkey. I also use Linux and Mac, and have received the same error with this new account. Who knows maybe it's the age of the account.