I've uploaded one trick from the 1991 Powell Peralta demo in Bath.
Hopefully at some point I'll have time to upload some more!
The demo featured Bucky Lasek, Tony Hawk, Curtis McCann, Mike Manzoori and Nicky Guerrero skating both a temporary vert ramp* and the classic Bath mini/midi.
Maybe one day I'll find the footage of Jeff Phillips, Reese Simpson and Monty Nolder skating Bath from around the same era. (Oz-cabs, have you got that tape?) Plus another Powell demo from a year or 2 before with Hawk and Lance.
*This was before the permanent vert ramp, which went up in about 1994 or 1995?