So I shot this footage over the weekend and as I was looking back at the exported HD file, I noticed quite a bit of artifacting and pixelization during high movements. Thought it was the codec, but I rewatched the source files and it's there. Is this a 7D limitation or did I do something wrong? shot at about ISO 320 F8 on a 50mm 1.4

Here's the video...went to a dog park over the weekend. It was actually kind of fun, freezing, but fun.

Dog Day Afternoon on Vimeo

It's probably your export settings regarding the bitrate. If you export with too low a bitrate you will see pixel noise and artifacts.

Fast camera movement with the 7D and any HD DSLR creates problems, try filming some locked down shots and see if you get the same artifacting etc.

Nice story though.

also if you are shooting on f1.4, depth of field is too shallow, most of your screen is blurred (which will be filled not-so-clear pixels.).
I don't think you are doing anything wrong with codec or exporting,
Just try to shoot maybe with 2.8-5.6 and try to get some stuff in focus.
Also running around dog is not the best thing to shoot in DSLR with wide open 1.4 aperture.