To authenticate with the YouTube API, you need to obtain an access token. You can do this by running the following command:
frame= 63000 fps= 0 (finished) size= 45678912kB time=00:42:15.00 video:42612kB audio:3050kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.3% upload s02e06 ffmpeg
It wasn't enough. The upload pipe was starving. The encoder was working hard, but the network wasn't getting the data fast enough to the other side. To authenticate with the YouTube API, you need