FADE fades to black, obvious.
ENHANCE just sharpens, and not very good -- in fact, really bad, since composite.
Audio is just a weenie mixer. A $50-100 Behringer/Tapco/Mackie would easily outperforms it.
It's not garbage -- that's gear from Sima and Archer -- just not very useful. This is the sort of thing that intro-level high school kids would play with to learn analog video in the 80s/90s. I don't remember this being very expensive, couple hundred bucks new at most. Under $25 is probably fair market value now.
That Youtube video is amusing. I'd not at all be surprised if the box caught on fire. Beware of faulty gear. I speak from experience!
The only value is history or nostalgia.