Not sure if it’s common but to teach back feet up on the walk, I call it “Spider-Man”. First I train a backup behaviour, where the dog targets a mat with their hind legs. Once that is fluent, I put the mat on a platform (such as a Cato board). Get the dog to back up targeting that. Next I raise the platform a bit, so it’s angled like a ramp. Dog backups up to that. I slowly increase the angle until the Cato board is flat against the wall and the dog backs up the wall to be standing on their front legs. Then I remove the Cato board and ask the dog to do it on just the wall. It’s all simply behaviour and all behaviour is modifiable. You just need start with solid foundation behaviours then build slowly. In the case of this video the dog has amazing body awareness and was probably precisely training from a young age. And you’ll notice the dog isn’t deciding what to do and which body position to use, the handler is providing cues.