Probably the only autopause extension that works AT THIS MOMENT and with YT's new experimental player, so for that I am grateful. Though it does need improvements; the video pauses inconsistently anywhere from one to five seconds in. The goal here should be so that it doesn't start to play at all. This goes for the new and old YT players.
I'd assume the auto-HD part works. IIRC YouTube already has this option, but this extension allows you to set a specific priority, which is nifty. I personally never have problems loading 1080p/60FPS so I am unable to test how well this priority system works.
3 Stars for basic functionality and usefulness. Could use improvements. Inevitably, HTML5 updates will break the autopause function for any extension like this, so I can only hope the author keeps on top of patches.