IIRC even WC Prophecy video was heavily compressed (but less than the two previous games, of course). WC3 was 3 CDs and WC4 was 4, and Prophecy was a single DVD, but there was a jump in texture quality and resolution between the two as well.
I think there's a mod that replaces the videos with upscaled versions, but for sure, getting access to the raw video would be awesome!