Marty, I've only seen the stretch of the Ocoee that was used for the Olympics. I bet there are tons of videos on the youtubez about the Gauley, some shot by professional video boaters. This is also an add-on sale: some guide companies will film the carnage, whip together a slick 20-minute movie with slow-mo replays of the raft flipping set to the jams of some local band, and sell you a DVD at the end of the float. Pretty cool souvenir to share with friends.
The Gauley has big water and challenging rapids, but it's mainly pool-and-drop so you'll flip, get thrashed around a bit, then pop up downstream in a calm stretch of water where you can regroup and get ready for the next rapid. I'm not trying to freak you out, my cautionary comments are mainly tongue-in-cheek from my days as a rafting guide. The Gauley is run safely by thousands of people each year and is not an opportunity to be missed. Just don't expect a theme park log flume ride. If you've rafted before, are comfortable swimming, and don't get freaked out underwater, you'll be fine.