Well, there could be a few things in play here.
One is that many of the content providers (cable/sat) can often compress the signal as it is distributed. The other is that jerky motion can also be attributed to a weak signal. Since the units don't have "static" like the old analog televisions do, frame freezes occur instead with a weak signal.
Now, if the signal is constant, and the AutoMotion Plus is causing a jerky or "watery" motion, it may be that the signal is being over processed, in which case, the best remedy is to adjust the AutoMotion Plus setting.
Keep me posted.
My question is somewhat similar to the other question a couple posts down about automotion plus. When are you supposed to turn it on ? I thought it would be great for sports like the other guy. Now I'm not so sure. It seems like it makes the movements unnatural at times. Here's an example: I'm watching the White Sox game this afternoon and they cut to Jim Thome at first base and when he bends down the picture loses focus and gets jerky for a couple seconds. I would say that it looks similar to when you put a dvd in still mode and then hit the forward button one by one to move the picture ever so slowly, but with the automotion plus it's 100 times faster then the dvd still frame look.