In this much talked about Van Halen video, you can clearly hear it's only Eddie who is out of tune.
I agree, a quick guitar switch could have been done. He looked like he was enjoying the mess he was making.

After the original band fired David Lee Roth, Roth went on sounding great as a solo artist.
The saddest thing this was Eddie's drug use. He's been in and out of rehab and even had thraot cancer and still refused to admit he's ever had a problem.

I saw a press conference when David Lee Roth and Eddie Van Halen got back together and Eddie couldn't even speak. And it wasn't his throat injury. He was wrecked out of his mind.
I watched him looking so lost. It was very sad. I do wish him the best and hope his habits don't rub off on his son.