This was my first thought as well. However, I can think of at least one possible disadvantage --
If these "enhanced" videos proliferate, then as a side effect there will be less desire for the original "source of truth" videos in grainy B&W and low framerates. I.e., this scenario: the original, primary-source video, based 100% on reality, gets 100 views on Youtube while the same video artificially manipulated to look better gets 100k.
Eventually the enhanced one has replaced the original, and possibly even the original gets lost, and in the future historians will only have our grossly-artificial reinterpretations of the video instead of the source of truth.
(but then again, YT is not exactly a historical archive, I'd imagine the originals should be archived properly to prevent this)