Not the best test, as my old Macbook (2.16 GHz C2D, 2GB DDR2 ram, 320GB hard drive) with the Intel GMA 950 integrated graphics can play it at 720p, full screen, without issues, only my fans spinning at full speed.
Now, Apple has a site with HD videos, most of them in 1080p. The link is:
http://www.apple.com/br/quicktime/guide/hd/
Most of those videos will run like a powerpoint presentation when I try to video them in 1080p. It will drop frames, play scenes choppy, and my machine will sound like it's ready to blast off down a runway.
This video in particular will make my Macbook cry:
http://www.apple.com/br/quicktime/guide/hd/bbc-nhk.html