That sounds like what Nvidia's G-Sync does. A in-monitor computer buffers frames and displays them at a rate specified by the computer.
http://www.anandtech.com/show/7436/nvidias-gsync-attempting-...
It sounds like it indeed. Although that particular implementation won't go below 30hz so wouldn't fix this particular case.
I see what you mean. Doesn't the HDMI standard have a way to fix this? It could just have a mode where you have 30 frames per second sent to the screen with the indication of which 60hz or even 120hz timeslot to use them in. It might need a little more/faster memory in the screen but should work fine.