I had a shoot last week with my 7D. I've reviewed all the footage through playback on the camera itself, and everything looks fine. However, when I transfer the footage to my computer for editing, I've been getting video artifacts on all the clips. I played the H264 from the card itself while in my card reader, played it after transferring a file to my laptop hard drive, and played it after converting it to ProRes422 HQ. I've tried Quicktime Player, VLC, and Final Cut Pro 7 to view the video files, and the artifacts are popping up on all of them.
I went back and looked at it in my camera's playback, and the artifacts are not present. I had shoots before and after this shoot, and none of the clips from either of those have any problems. If anyone has any idea for how to transfer these clips to not wind up with artifacts, or something I can do to fix it, I'd love to hear.
Can you post some screen shots of what you're seeing? That may help those on here to answer better.
Sounds like the artifacting may be in your footage. Judging much of anything on the DSLR monitor won't do much good as the small resolution of that monitor hides many problems (artifacts, hot pixels, focus, etc.).