And if Wikipedia is to be believed it's presented in a eye wateringly high resolution of 112p.
This high of res.
Edit: Of course the bit rate was pretty damn low as well. Here's a comparison video I found. This comparison uses the higher bit rate version from the Shrek GBA video cart not the Shrek+Shark Tale video cart though so keep in mind, this is the better version.
Sweet sweet digitally compressed movies. Two of em, 64 mb total. The next best thing I can remember were PSP movies, l my parents of course never let me buy them, but my buddy had a copy of Final Fantasy Advent Children, a whole 1.8 gb (if two sided). Glorious handheld videos to watch during a bus ride home.