Earlier in the week, I was out on a shoot for a wedding. Upon reviewing footage from the reception, I noticed that some clips had intense artifacting and codec degradation. After discussion online, one user suggested that low shutter speeds (below 1/60 at 720P) would result in such footage. Particularly if the clip bitrate was low. Research showed that the clip was averaging 4Mpbs, well below where it should have been.
Result: When shooting at 720P, shutter speeds below 1/60 will result in codec degradation, most noticeable when the camera moves or the image fluctuates in exposure rapidly. Furthermore, the bitrate for that clip will be extremely low.
Thanks to user rambooc1 and the rest of the contributors at dvxuser.com/V6/showthread.php?255465-40-Mpbs-Codec-Breakdown