My left hip joint isn't as flexible as it ought to be. I started trying to search for it on the internet. I was looking for a couple of things, including what that condition is called. I tried doing what the video clip called for.
But sitting on the floor with my knees bent, with the knees aimed at the ceiling, then lowering one knee to the floor, then the other, seemed to help.
I did OK with the right knee, but the left one didn't want to go all the way to the floor. It did loosen up, though.
The photo I saw of the stretch they said was good for that showed the right foot flat on the floor (sitting in a chair) and the left ankle resting on the right knee. Resting the hands on the left knee seemed to complete that move. It hurts to do it.