I’ve been using the YouTube Data API v3/Google APIs Client Library for Ruby for over a year now to upload, update and delete videos automatically. I frequently receive errors from the API when trying to set the thumbnail image for a video right after it has been uploaded (something about a rate limit being exceeded and having to check some quota), but I am always well under the service quotas, there is no mention of the error in the documentation, and resubmitting the thumbnail always goes through so I just resubmit the thumbnail as needed. Most of the time everything works as expected.