I dunno. Things like cocaine, roller skates, etc, were all 70s trademarks. Just because it's a tracking shot from behind the skates wouldn't make me think PTA borrowed it.
However, many of the porn scenes in Boogie Nights WERE borrowed directly from 70s porn movies. And a lot of scenes from "The Dirk Diggler Story" by Amber Waves were taken from Exhausted, a documentary about John Holmes. The old Criterion LD had these clips, but they didn't get the rights to put them on the DVD or Blu.
CINEMA PAFF - Your BB-Movie Showcase *
* - The extra B is for BYOBB