It was not a loop but a negative-g pushover. Very inconsiderate with a passenger on board who is already airsick and has the (open) bag to prove it.
In addition to this:
- Looks like a C172 to me (but I might be wrong). Are you, according to the POH, allowed to perform negative-g manoeuvres with pax and baggage in the back? Isn't this restricted to the utility category, or plainly forbidden altogether?
- In any case, it's a good idea to fasten and tighten seatbelts before attempting this sort of stuff, and secure the baggage. Those girls came off their seats something like 10 centimeters, and the baggage was free-floating.
As said, the pilot's an idiot and deserved being drowned in whatever was left in the bag after landing. Poor girl.