The original intro video I think was like..430x320 or something resolution.

So yeah, stretching that to 4k is never going to look good. its the same problem the CnC Remaster team ran into trying to upscale the original mission intros, old games used very low resolution videos to fit on their disks and not take a super computer to play and that is part of the charm for sure, often lower than the resolution the game itself would be expected to be played at, and theres just not enough meat there to stretch it beyond resolution doubling.