Hmmm, Its hard to say what happened hey? the fact he says its a maiden, could mean its the first time he flew an inspire, in which case we may suspect he did something wrong. He seems to know what he is doing though, and the flight was controlled enough to suggest some experience, plus he says it performed as he "expected"
The fact he did a maiden with the camera on tells me that he isnt too experienced.
Now. He says all link was cut....... okay..... then the drone goes up to 500m, (coincidentally the max alt permitted?) it turns 180 degrees, and then you can see it decend.......... this all looks like a homing routine set to 500m safe altitude to me.
then the inverted flight? No idea.... maybe a lost prop? you can see the drone yawing in the final stages of the video.... perhaps it had also leveled, beacause it didnt seem to be coming down fast enough to be inverted.
all in all very scarey indeed. Either due to pilot error or machiene, either way, I owuldnt want to be in that park when something like that happens.