You know, I think that most of the on-ride shots are from people who are actually on the rides. I've done those myself. You need to make sure that your camera is secure (e.g. good strap) and have a ziplock bag or other protective covering for your camera. This is coupled with ensuring that you put the camera away before it gets damaged by water or another unhappy event. For example, I was on Kali taking pictures of my family before the first raft drop. I promptly put the camera away before anyone got wet.
Some of the shots are of the photos taken on the rides by Disney. To capture these shots, you need to take a photo without the flash of the tv monitors after you exit the rides.