Zuma a pole lathe, or spring pole lathe, is basically a half bow above the lathe, attached to something solid, tree, or a cross bar. the string is passed down to the work piece, and wrapped around it once, and then down to a foot pedal. Or the opposite direction, of from the pedal up to the half bow, and looped over the knock. Anyway, you just step on the foot pedal, and it turns the stock, and let your foot up, and it spins in the opposite direction, so you can only use the gouge, or other chisel, intermittently, as it spins one way, and then the other, but it has been in use for quite a long time. The bow lathe has been in use for quite a bit longer, and is still in use, as can be seen, in the video, the advantage of a pole lathe, is you can use both hands, the disadvantage, is it is bigger, and not as portable as a bow lathe, and takes up a bit more room. And requires you to build a solid frame for it, and the foot pedal set up. But it is super simple, and the frame is not difficult to build. Just Google pole lathe, or spring pole lathe, and you can see it's pro and cons, as compared to the bow drill. Thanks for sharing the pictures, that is a cool and simple set up. Obviously the guy in the picture didn't have any problems adapting to it's use, and is doing quite well with it.
Wayne