I was informed by my normal reptile vet that probing should ONLY be done by those who know what they are doing, especially with babies unless they wish to wish extreme damage to their tiny little reproductive organs. He almost suggested popping to be the safest. I don't prefer it, honestly. But I haven't had to do it. I have literally bought every animal already knowing the sex before purchasing him or her. I believe that video was extremely helpful so thank you!
Not that I don't think "inexperienced" persons inappropriately performing popping could do equal damage, but a probe might be a bit worse. Just saying.
Maybe look up some serious videos on probing? It's really a careful practice. You're going inside something very itty bitty. I know I can't do it. My hands shake so I am probably screwed forever anyway when it comes to the matter.