It's never been released on DVD. Or VHS for that matter. So if you find a DVD copy somewhere, it's a bootleg, and it probably won't look much better than those YouTube videos.
A lot of PBS stations aired it in the 70s, so I assume there are a number of 16mm prints out there. Or copies on those big U-Matic tapes (in landfills across America).
It would be nice to see a non-shitty version of it one day. We have - uh, I mean the world out there has - a pretty good copy of the whole hour, but it's not DVD good. Just okay good.