With the Ultra TV here the screen captures themselves are at 720x480. With the screen maximized it appears about but not quite as high as the desktop here. You'll find that video generally uses inbetween sizes rather then what is the standard desktop settings of 800x600, 1024x768, 1280x1024, and higher.
Actual the resolutions will also vary depending whether the video was created in NTSC or PAL. Resolutions can go from 620x400, 646x486, 768x576, 800x480, 848x480, and upto 1200x800 when capturing. On dvd video in mpeg II format you would see 740x480 and 720x480 for NTSC as well as 704x576 and 720x576 for PAL,