I’ve got the 60" version of this set. What do you mean by “jitters”? My ATV2 doesn’t like 1080p stuff and even some 720P content. One thing I notice is that the FPS are critical on some HD content. Do you have Handbrake? grab one of the .mkv files that’s giving you grief right now and load it into handbrake. Then, choose the appletv2 setting as output. If you look at all the different outputs, you will see that the appletv2 setting doesn’t really have too many differences than the high profile or normal settings but pay attention to the framerate preset on the appletv2 preset. This preset ENSURES that the video frames are correct and that the ATV will be happy.