Media reported:"after undergoing maintenance", in an earlier post. One would think that the ground run part would include trying small control movements and looking for the correct rotor response ( assume one can move the pedals on this model before starting the engine and confirming that control input is free and properly phased. Then, before getting energetic about getting up and away, lift it to just skids beginning to break ground and again, small control inputs, after which a very slow lift to a low hover and repeat the control inputs etc. Not what the video shows, but then again, perhaps something went amiss as they were just slowly lifting and the result was beyond their ability to perform any corrective action. Test flights following maintenance have to be treated very carefully.