pupunzi/jquery.mb.YTPlayer — pull request #43 by Brandl (2014-07-22 17:05:40+00:00)
Title: Prevents getting stuck, if embedding is restricted

There are multiple reasons for this to happen, most notably, if there is a copyright claim on the video or age confirmation is required...

Logging it to the developer console, is a personal preference.
At least it would have saved me a lot of time, because if the video doesn't react to pressing play, I was at least expecting some sort of Javascript exception, which would explain this to me...