No. No easily available spray paint is going to weaken the plastic.
Krylon fusion bonds to plastic better having a reaction with the surface plastic, but doesn't weaken it and that's the closest paint I could imagine he used.
Don't use Acetone as a previous post suggested. It is a fairly strong solvent and will remove the original finish on the bindings as well. ALSO melts the surface layer of plastic giving it a glossy finish.
Drop some acetone and Styrofoam and it will eat straight through it. Wouldn't recommend it on bindings.
My best bet is some denatured alcohol (commonly known as rubbing alcohol) but try to find some containing a higher alcohol content like 70%.
Get a fine grit scotch brilla pad and have at it. Use some elbow grease but find a good balance so you don't scuff up the original binding. Guarantee you'll get the majority off.
Something else that works SURPRISINGLY well is brake fluid. That stuff eats through ANY spray paint. I use it quite frequently to remove over-spray from my projects.
Also will not harm plastic, just eats paint. And I doubt it will harm your underlying finish only because it has been cured more appropiatly then the spray paint. Just make sure you THOROUGHLY rinse the parts with water after finishing. Water breaks down brake fluid.
Sparknotes:
Try alcohol/brill pad first, then brake fluid for the hard to reach spots.
Avoid acetone.
Paint won't weaken your bindings.
