That's not against the rules. It's only a problem if he copies the replay and reposts it as his own. But even then I doubt much would be done seeing how the replay was in a sense "given" to him.

Otherwise, Wikipedia Toribash moves would be an issue.

Anyways, when I go to make openers, I think about how I primarily want it to look based off of my imagination, and I build off of that. Use things like styles of fighting/acrobatics that appeal to you. An original opener is always the best kind of opener. ;)