@ Trent,
I'll second your statement. AMP was working as expected until the 1.5 RC upgrade and then the buttons disappeared from the Visual Editor. So, then I posted about it on the AMP forums with no response.
I figured I'd wait until the 1.5.1 upgrade to see if this solved the issue, but I've just upgraded to this latest version yesterday and the AMP buttons are still missing. I'm really hoping that there will be an update to AMP or that someone more knowledgeable than me will be able to offer a fix, at least something for me to try.
My whole MU site is geared toward media creators and having an easy method for my users to add video is essential. I'm keeping my fingers crossed, but I'm afraid I'm going to have to start the search and testing of different video plugins.