The last roller coaster I went on was at Alton Towers over 25 years ago. although I was strapped in I was slipping out. I was terrified I was going to fall out. When the ride ended I reported my experience and was told they would check it out. I have not, nor will not go on a roller coaster ever again.
I usually go to a theme park at least once a year. Last time I went to Thorpe Park and can honestly say that it's the first time I've ever felt fear. My hands were sweating so much I couldn't hold on...
It could leave the track easily enough. It would be getting back on that might present problems.
We're looking at a bit of clever image manipulation. Health & Safety would never allow it.
One of the young factor-fictions is very knowledgable about theme parks all over the world and said this is a well known 'fake' clip that's been around a while. Shame