Agree.
The speed of the rotation is too fast for a tail rotor failure.
All rotary wing pilots are trained and practice tail rotor failures (both full left and full right pedal) and while they can make life interesting, are not impossible to control.
An aviation accident blogger interviewed a US test pilot with some 7,000 hours on rotary wing and said the mast bump theory as unlikely as there has only been 1 documented accident with mast bump on a 206 in that models history.
In that case the tail boom separated at the far end and not near the cabin in these videos.
Also in that case, a large portion of the main rotor blade sheared off and in these videos it has been pointed out that the rotor blades appear complete and attached to the mast and what appears to be a portion of the transmission.
He, quite rightly, is saying that no-one will know until all the wreckage is recovered and inspected.
A transmission failure would give a yawing motion of that severity.