Not the projector. Nothing you can do about it. NBC needs to buy better equipment or tweak what they have better, and stop wasting BW on sub channels. It's not really a flaw with HDTV. Other channels encode fast motion into the same amount or less bandwidth that looks better.
That's MPEG-2 compression. There's not enough bitrate for the motion. NBC sends your local affiliate a 45Mbit/sec feed that your local affiliate recompresses to something smaller. The max would be 19.2Mbit/sec. However, usually the local affiliates waste some of their 19.2Mbit/sec on sub...