Rockin' Roller Coaster is right at takeoff. You're limited in poses by the restraint harnesses though.
Tower of Terror is the second drop. They do the initial plunge, and when they lift you back up, that's when the video/photos kick in (they also get a quick vid clip earlier).
Splash Mountain is at the final big drop, so hold the pose just before you go over.
Test Track is right as you head to the outside portion of the ride, so get in position just before the doors open to the outside track.
Space Mountain is right at the beginning, almost right after they load you into the ride - the cars head around the curve to start heading up the track to the bulk of the ride and they snap it then.
Buzz Lightyear is the one I can never keep in my head - so much going on in that ride I always forget where the camera is (and I'm never posing anyway because I'm too busy trying to boost my score!)
7DMT I've only ridden once so I didn't note where the photos/videos were taken.
I know there are others with photo options, but those are the ones I remember off the top of my head.
