I have so many videos of my boyfriend jacking off (
http://trixieshouseboy.com) that's what I usually use for a quickie, or some incestuous Jetson toons on a slideshow. Or I use one of the many plugins in our own members areas.
I've also masturbated a lot to a video from Lori Anderson's free tour wearing duct tape on her mouth while a guy keeps telling her to "suck it" on
SweetCamGirl (scroll down - it's the one called "Leather").