Oh, it's MPEG4 alright. DivX to be exact. It's also MPEG4 and an AVI container.
Let's see how it fares against MPEG4 AVC, shall we?
And the results are in. RAR: 150 MB vs 150 MB.
7zip: 152 MB vs 150 MB.
I can instruct how to recompress and verify these results, if you want.
But it goes to show that compressing a video using good video compressing yields in little or no saved space.