The author of the YouTube: Auto Buffer and Stop AutoPlay Greasemonkey script has released an updated version (1.2.5) on April 8th. Recently Google/YouTube made changes which caused this script to stop working. Also new with this version, if an HD version of the YouTube video is available it will automatically be selected (this can be an issue for folks with older systems).
Edit: There is an ‘Autobuffer Options’ button just below the video title and to the right of the ‘Subscribe’ button. Options includ:
- Auto HD
- Hide in-video-ads
- Hide annotations