It looks like you need to adjust your mechanical trim. Loosen the servo mount and slide it until the tail rotor is angled about 5 degrees, blowing air to the right side of the heli. Try to hover with HH off. Adjust your trim till it holds relatively steady at chest height. Then land and move the servo again until the blades are in that same position with the trim at zero.
If that doesn't fix it your gyro may be reversed for your application.

Joaquin