Safari will shift the color of MPEG4 videos while decoding in the browser, which means that even if you copy the pixels using canvas you will NOT get the correct colors.
If you want to match colors in Photoshop, After Effects, or Quicktime, you will find that this color shift persists, and is actually different in each application.
Thanks a lot, Steve.
The only way to get the true browser display colors is to take your MPEG4 and open it in Safari, then take a screenshot and work from there. You can also get the same color shift if you drop your .MOV file into Safari as you would with the MPEG4, so this is one way to get a high-res screenshot.
Someone needs to burn this browser with holy fire.