They're attempting to claim that it's a violation of the professors' intellectual property rights. I've also heard of attempts being made to make students sign NDAs, or at least seen it talked about (not sure how "real" that one is).
These tactics are purely an attempt to hide the real issue, which is the extreme political bent many professors bring to the classroom, often in inappropriate ways (massive attempts at "feminism" indoctrination in Freshman English Comp & Lit classes, that sort of thing).
With the venom these professors force their students to listen to, you would expect the students to offer the tapes of their class "free" to the alumni group, in the hopes that indoctrination might be eliminated at UCLA.