I saw the video, too.
Dustin was flying about a meter or aprox. 3 feet from the ground when he turned sharply to the left at full forward throttle. In this attitude the rear rotors are pitched higher than the forward to be at maximum forward thrust. However, as the drone pivots on it's axis the front rotors lose laminar flow of air over their top and thus lose lift, causing the nose to dive. Remember, the rear rotors are still slightly above and thus will over-drive forward thrust at an even steeper angle downward. Added to this equation is what is called "ground effect" which reduces drag, further increasing forward velocity but without generating lift. Ground effect also negates any barometric effect up to two meters AGL (above ground level). I'm not sure that an advanced algorithm could have even compensated that quickly, any DJI drone would also have crashed under similar circumstances.
I fly the H501S with the same barometric altitude hold sensor. I have learned through similar errors to increase my altitude a meter or two before making such a tight turn at full throttle. This was entirely pilot error on Dustin's part
Hope that helps.
