Went to the Apple/Sony XDCAM HD Road show today in Seattle.

[Dan Riley]

Well Sony, of course, claims it doesn’t matter, but like I said, I’ll rent it and try it
on a shoot and see how everything goes. I’ll even do a little blue or
green screen tests to see about keying. 4:2:0 actually ends up being 4:1:1
which was not the best sampling for chroma keys in my experience.
But I was doing SD, so maybe it’s better in HD.
Here’s a nice reference site:
https://www.answers.com/topic/ycbcr-sampling

Dan