I know I’ve talked about reference before, but I wanted to reiterate: It’s okay to stop a movie and draw the gestures. I once was yelled at by an student artist who was adamantly against using reference material, but I have never heard of one professional who didn’t.
If I was going to use any of these poses I would certainly doctor them up a bit more to make them uniquely mine—one of the things I like to do is to push the scene forward and try to imagine what it would look like if the character(s) continued in their current movements a little into the future—it helps me focus on the structure rather than relying simply on what my eyes are seeing.
But there’s nothing wrong with “swiping” or simply lifting an identical image for your own study. I find that if I’m having a difficult time with a completely unrelated pose, say of a man doing yoga, drawing out ten men of similar body types from my unrelated reference material will help me clear that hurdle. All I need sometimes is that one push to remind me of proportions or bone/muscle placement.
Also, for digital artists, I’d advocate warming up in this way with a tablet. For some reason, drawing easy gestures from reference with a tablet forces my hand to use the correct pressure—something I struggle with in my real work if I don’t warm up.