It's very simple I had the same issue. It's the hashrate of the video codec you are using. Before the latest update,  there was a hashrate monitor. Anything genrally over 2.1MB per second would fail. Anything below 2.0MB per second went up with little issue. You may need to reduce the quality of your video to get the hasrate lower and you should have no problems uploading. If you have a Youtube Channel and you are downloading old content, the codec/hashrate of what you will get will fail to upload. It may be something that youtube did to counter people downloading Youtube content and uploading it to Dtube(a ton of that happening). This wasn't an issue before the last update even at higher hashrates than I mentioned before. 

Sorry if I didn't explain this as well as a tech suppport guy. I'm just a regular person that doesn't care about proper grammar  usage or communicating written or orally to please the queen. Any questions let me know. I hope this helps.