About black levels, I think the tv reccomendation is just so it shows up on most tv sets which may not have the full range from 0-255. My family's widescreen tv has about 1/4th the contrast ratio of our analog rear projection. If stuff like the opening of ET looks completely black, then too bad. I don't like the idea of compromising the picture just so it shows up better on a tv. (isn't pan & scan another example of that?)
I don't know if that is the actual reason. But my video production professor told us there are legal black/white limits by the FCC in the US. He's also mentioned many times before that video basically has the wide range from dark grey to light grey.

And would Arnie be able to post his laserdisc vs Gout caps? I've seen the comparisons already here but those might be cool.