There's an AU plugin that cleans crappy Youtube video into awesome stuff!
It's called "Youtube crap into
Garageband gold" plugin from Waves. Go get it.
Sorry, I couldn't resist.
Bro, there's little you can do. Right off the bat, you're getting bad live recordings from the 70s. On top of that, you're downloading it from a crappy Youtube video converted into a bad Mp3.
If you find the recording is muddy, I suppose you can cut a tiny bit of the low frequencies, but that won't do wonders. You can't turn a mono recording into stereo without getting individual tracks. There's nothing you can do to "enhance the quality." Crap quality in is crap quality out.