I guess you could be looking at an interlaced signal ? They tend to give a difficult-to-describe unpleasant effect during fast movement.

Last I heard a mix of 720p and 1080i was being used depending on the content (or on the station, I forget), not sure if that is still the case. Anyways, action + interlaced HD = funny effect.

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8