Disclaimer: I'm writing about a clip over 10 years old, I'm 95% sure it was Petra. If you have evidence toward the other 5% feel free to reply here.
It's another clip I wanted to put in the Rackumentary but couldn't locate. It was a late night tabloid or multimedia TV show like Inside Edition or Night Flight or even a long dead flash in the pan newsmagazine. The topic was breast implants and contained mostly statistical information about the growing popularity of the procedure (this was 90-92?)
That was the news part. The tabloid part was for visuals we got Playboy DD-cup Playmate Petra, fresh from her Playboy debut at the time putting her spandex straining rack through a rigorous workout at an LA Gold's Gym. There she is doing squat thrusts, pontoons heaving toward the camera. Next, a few minutes on a stationary bike, wonderful posture, back arched tits undulating right to left to right to left. A few jumping jacks kaboing, kaboing, kaboing. I burned a few calories just rewinding this clip.
One other subtle touch, all this to the accompaniment of Rusty Warrens' classic undergound boob single "Knockers Up" (the original adult comedy anthem).
Anyway, the segment ended with the usual caveats about having big boobs, i.e back pain, hard to find clothes, etc.followed by an unexpected and somewhat incredible Petra anecdote extolling the virtues of being a bra buster.
Apparently, one day Petra was doing a little underbody work on her classic VW Beetle. Horror of horrors, the jack collapses leaving Petra pinned beneath a few hundred pounds of German engineering with nothing in between but her magnificent airbags. Good thing that, during recovery her doctors informed her were she any less well endowed she would've sustained near fatal chest injuries. The final shot, the amazing Petra standing in a doorway in a sports bra with the glowing tit endorsement "...And they Even Saved My Life!"
Damn, I really gotta find that tape!