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.
Not gonna lie, 112p video is actually kinda amazing for a gameboy advanced cartridge. I dunno how much space that'd take up, but I'd bet it's more than your typical GBA cart.
They also ran at a much lower frame rate and compressed the audio quite a bit
Basically they had to fit both movies in less than 64MB.
To be fair, we still do a similar thing with movies today when we want to send them on discord, crunching it down to 25-50MB
And then there's this.
I wasn't expecting to watch Tremors while sitting on the toilet this evening but here we are.
That makes two of us
Careful, they can sense movement