This is pretty n00b of me, but ... who's that with Brian at 2:20? link
Looks like 70s Dave Gilmour, but he wasn't a Les Paul guy.
...as for the video itself, once again the utter brilliance of Good Company just doesn't get the praise it deserves.
One of the Thin Lizzy guys perhaps? They were Les Paul players, toured with Queen and, if the guy in the picture is Snowy White, even have a connection to David Gilmour. Who, FYI, recorded the solo from Another Brick In The Wall part 2 on a Les Paul :-).
Gilmour rarely played with a LP between 1970~1978. In The Wall records (1979), he plays Another Brick in The Wall's solo with his LP. He also played at the tour shows (1980~1981) with the LP, at the Another Brick solo (link, but in The Wall tour (1980~1981) he hadn't the long hair anymore.
This is a freakin' puzzle. I'm trying to find anything about this image for hours, and haven't found nothing. Jesus Christ.
Yeah, weirdly it's not that easy to date the picture based on Bri's appearance, but I'm going with around 1991. His hair's got that red tinge that I don't remember being present at any time other than around Innuendo.
And if that's right, then the gig must be one of the ones here - http://www.queenconcerts.com/live/brian-may/guest/6.html - which should hopefully narrow things down.