The butterfly guard, to me, is the best “learning” guard. By that I mean, for my experience with jiu jitsu, it’s the guard that most prevents stalling-type tactics in training and allows me to explore different positions, off-balancing techniques, grips, sweeps, back takes, etc.
From the butterfly guard, I look for the one-legged x-guard, regular x-guard, reverse de la riva, etc. I haven’t, however, looked for the obvious leg locks from the x-guard position. There’s a knee bar, and there’s also the basic straight footlock. In the following video, Marcus “Buchecha” Almeida shows this basic footlock. To me, these type of videos are what YouTube is good for: high-level competitors showing jiu jitsu fundamentals:
I’m still focused on controlling and dominating the butterfly / x-guard positions, so submissions are still secondary for me, but it’s good to start thinking about these things, so that I can start to notice openings when they pop up.