"They put have a special tailskid installed, rotate very early, and gently set the tailskid on the runway. You'll notice the rotation is somewhat quick, yet you don't see sparks until several seconds after the initial rotation has stopped. I imagine there is a tailstrike protection control law which prevented a tailstrike on the initial rotation, then after the initial rotation the protection was shut off, and the tailskid contacts the runway. Then they drag the tail until it lifts off.

Vr speeds are set by several parameters from several different tests, not just an increment from Vmu. You can strike the tail at airspeeds well below Vr if you mistrim the stab and/or yank the stick full aft.

Some test pilots might call Vmu a fun test. In a tail geometry limited plane like this you must accel above stall speed to be able to liftoff, so there's still an increment of margin before stall. Certainly you notice the pilot push to a slightly lower AOA after noticing the increase in AOA after liftoff. If you are all engine, probably no dip in airspeed even with that brief higher AOA part after liftoff..."