That would probably have a pretty strong effect! You'd pretty much have the screen creating 1 pixel of the video image with 4 of it's own pixels. Meaning it'll look pretty blocky and not very smooth (image wise, not movement wise).
I only have a 1200 x 800 monitor that i got for free, and mine looks crap. I'd hate to see it on a REAL screen!
Works the other way too though! I had a discussion with SWMBO a while back because we streamed a film online. She wanted to pay extra because 'HD is better'. I argued that if we did that, it would be a waste because it's only a 26" TV and we sit 8' away from it. So our eyes wouldn't even be able to tell the difference. Sure enough, we watched it SD, looked great. Everybody is happy.
But another time a mate of mine wanted to show off his 52" LCD TV so we watched a DVD..... It looked awful! It was like watching a cutscene on an Sega megadrive game! But he didn't notice, OR care for my explanation about how DVD is actually very poor resolution.
What was my point?...
Oh look, a badger!