There's already a question asking about how to stop YouTube videos from automatically playing. However, the solution there doesn't satisfy me as it prevents the video from buffering in the background.
Is there any way to prevent YouTube from automatically starting the playback, while still allowing the video to be buffered? My browser of choice is Firefox so extensions would also be valid solutions.
I would be especially interested in any solution that will allow me to choose the quality in which the buffering will be performed—for example, a solution that will allow me to always set videos to the highest quality mode available up to and including 720p, while still starting them at "pause" mode.