TIL I guess.
And since I don't qualify as a kid, I am guessing that most mid-twenties wouldn't know either.
I think vinyl was still sufficiently popular for most folks in their mid-twenties to recognize it. I'm 25, and several of my grade school classrooms had record players, not to mention all the homes of my parents, their friends, and our extended family.
But as far as I can tell, few folks born in the mid-80s had significant direct experience with records, to the point where there were cultural references to our ignorance. In particular, I remember a sunday morning comic strip when I was young that centered around kids not being able to identify a record player. We were right on the cusp of its obsolescence.
To wit, I couldn't tell you the difference between a 33 and a 45 (well, it's rpm, but are they different sizes?), and I've never owned music on vinyl.
I'd wager that people born in the 90s would be the first to be completely unaware of the origins of the record scratching sound.
Another anecdote: I heard on some NPR show that most kids don't understand what the sound of a record being scratched to a halt actually is. (This sound: http://www.youtube.com/watch?v=Wn6s1FE-yKQ) When asked, they describe it as the noise that is made on TV when you do a double-take.