I saw a great talk explaining linear algebra where the presenter used it to solve the angles of an arm joint to place an animated robot arm at a specific co-ord

I saw a great talk explaining linear algebra where the presenter used it to solve the angles of an arm joint to place an animated robot arm at a specific co-ordinate. I think it might be this actually, can't watch it all right now to check. Demo I'm thinking of should be https://youtu.be/3v75aX5-gSA?t=1436 https://youtu.be/3v75aX5-gSA?t=1436