The API quota for my project was successfully increased to 4M through the application process. This is confirmed in the details for the quota via the Google Developer console quota page for the enabled API.
Videos are, however, being rejected with this message after just the standard 50 uploads with this message:
Task 310: Upload failed. Exception: HttpError 400 "The user has exceeded the number of videos they may upload."
Here is an example of a successfully published video.
Thousands of videos are waiting in the queue from an event that finished days ago. Several people from Google have been trying to help but this morning I was asked to post on Stack Overflow.
This is a relatively new behavior, I was bitten by it as well. It seems YouTube/Google has no intention to change it:
https://issuetracker.google.com/issues/35919708#comment10
This isn't a project based quota which would have been upgraded. This is a user based quota which can not be upgraded. It means that the user in question has exceed their upload limit for the day. The YouTube API has a slightly different quota system than other Google APIs. The ones listed in developer console are just the general ones. You should check calculating quota usage
This quota should reset at midnight West Coast USA time. It sounds strange to me that you are seeing this after only 50 videos. I am not all that sure what denotes a user; it could be IP address or the authenticated user.
So Google support got back with a note saying that we'll just have to wait for the quota refresh... I can't even see any difference from the 'increased upload' capacity and the limit does seem to be 50 (roughly at least). I've asked them how long the anti-spam upload freeze actually is but I'll carry on breathing whilst I wait for that puppy.
Special thanks for help from DalmTo and halfer though.
Message from Google Support: