All well and good when the source catches up
But it's either going to try and fill in the missing 3 (at best) frames if we're talking about any playback today (i.e. DVD, BD, DVB-T etc).
I just realised yesterday when watching a DVD on my PS3 with a 60HZ TV, it seems that when you watch it frame-by-frame, it only updates the picture every second frame - so rather pointless!
However, it goes back to the aliasing argument. Most TV broadcasts are aliased to introduce forced motion-blur. But the sharper the images (as is becoming the trend with HD), the more noticable the transition between frames - this is rather evident in an HD panning shot, you can start to see it becoming jerky.
As said though - will be good for Q3 :-)