I thought the same thing when I saw this video a few months ago. :). I know it would take me a LOT of practice. Those girls are a very unique pair, that’s for sure.
I can do it with my right hand a bit–I guess decades of playing the piano where the orientation of thumb low/pinky high is the same (made it really hard when I started the harp and had to flip that concept around!), but left hand not so much. These young women have certainly found and developed a niche for themselves. I have people who probably would never think of listening to harp music outside a hospice setting sending me their videos all the time. It’s all good! 🙂
From guitar background, harp playing is reversing the high versus low sequence amongst the fingers of the right hand. But very soon the music decides where the fingers go. I do play the harp from column most mornings when reluctantly having to leave it and want a last touch / chord / phrase before really leaving. Again the sound determines where the fingers go.