Does anyone remember this? Fear on Saturday Night Live in 1981.
The basic story is that Fear were on the show as personal guests of John Belushi's - they were buddies. The kids slam dancing around the stage were (I think) mostly a crew of kids from DC - the Dischord kids (Minor Threat et al) and some others.
I remember seeing this as a kid and being pretty blown away, and it's still a cool performance. This sort of mayhem would never happen these days - this type of underground band or the slam dancing for that matter - too many lawsuits waiting to happen, too much insurance to think about, not enough records sold to warrant an appearance.