Wing Chun Kung Fu - One of my arts.
This is Muk Yan Jong 107 being trained for speed/coordination. It can also be trained for power/accuracy. I believe this child's mother trained him as this is considered a "female art" popularized by Yim Wing Chun's victory over a merciless, and feared warrior after training for only a short focused period with a Shaolin Monk, and a Nun Si Moo.
They sped up the video, but I think that does us a disservice. The normal speed would have been impressive enough.