I have tested this across 5 different 2010 Apple Units, using a different HD rental on each one, and found that it worked 100% of the time. This is just a temp fix but it will allow you to watch your movies without the jitter issue. 1. Rent Movie and begin watching. 2. Keep track of buffer level by checking white progress meter (up or down arrow on remote) 3. White progress bar is the buffer. When it reaches the end (100%), this is when the jitters will start. 4. Reboot the ATV (Unplug power then plug back in) 5. Restart the movie. The buffer should still be full and it will playback without issue. You may also be able to just rent and not start watching until the buffer fills. Not sure how that works. Point is let the movie buffer completely then reboot your ATV for smooth playback. I have not tested this on full movies since I did not want to rent 5 different HD movies. For one the 5 units are at 5 different houses and waiting for a full movie to buffer takes longer. I am going to try just one movie at my house and see if the above works for a full movie as well. Im guessing it will.