As long as you make sure your camera has a hand strap I reckon it would be fine anyway, because if you got discovered then you could say that it was secure and I'm sure they couldn't disagree. I mean, you have to take your bags with you onto corkscrew at Alton Towers, so it can't be that bad if you take items such as a camera onto a ride.
As for making sure you are filming good film, as in not just looking at your feet lol, then I think it helps if you has a camera with a little screen so you can see exactly what you're filming and you don't end up with the lense cap still on or something