There was a persistent rumour when that vid came out, at least in the circles I moved back then, that the lead female dancer was in fact a man. I have no idea why.
I've got you really troubled now, haven't I? That was the trick - I worked it out after a couple of years but I couldn't put you through that.
Like they say in Muscat, "If it takes you 20 minutes to work out if she's female or not ... you're already committed".
Currently enjoying All Sides Of The Roxy: May 1978, a new release of old Todd Rundgren performances. Too soon for YouTube I guess, so here is a suitable substitute: