The speck moves too fast to be anything but an insect in the foreground. Its sudden appearance could’ve been when it flew into the light cone from the floods, or simply near enough to the camera to be seen.
Some observations; after just the first half of rotation, it looks like the rotation was so rapid the resulting g-forces would’ve made positive control extremely difficult. Also, the aircraft rapidly built up a very high rate of descent. So thrust was lost from the main rotor one way or another.
It looks like the transition was above 300’, so sound would have been at least a second behind what you see.