On my 12" PB. All I can say is it's plenty good enough for me for $2. Full screen viewing. Not crystal clear. (Would imagine less so on our 20" iMac which I will test soon enough.)
Sound is very loud and good.
When it is in the small viewer mode in the artwork area, that is about what it would look like on an iPod. Quite honestly, I am pretty surprised.
I will probably download quite a few more videos. Will tide me over quite nicely on a plane in between listening to podcasts.