I didn't gety taught the rubber guard or the Lock down until I was about 8 or 9 months into my training. I knew about the rubber guard but never really used it. My hips are very flexible so I picked it up really fast.
I never even herd of the Lock Down until I herd a guy talking about it. And all it took was me asking him about it and he jumped into showing me it. It's pretty advanced stuff. The idea of it seems simple but putting it into practice is not. It puts a lot of pressure on the legs and it is countered pretty easily. I say just bring it up in conversation. I doubt he/they will have a problem showing it to you. No harm in wanting to learn them!!!
Credit to M.C !!