They were really lucky. If they were 12 floors lower then it would have ended horribly. I wonder why didn't the emergency brakes work immediately. Shouldn't it clamp down as soon as any elevator cable snaps?
It's not clear how fast they were falling; it may be that the brakes didn't kick in because the fall was slow.
Most likely the jolt was simply the rest of the cables catching the load of the cabin. If the brakes got engaged or the elevator ran into the buffer the elevator will not be aligned with the ground floor.
Glad to hear you got off with nothing more than a slight fright though.
I think this is very good advice for the US and western countries, where you can expect some technician/fire brigade to come and help. In the communist Eastern Europe of 3 decades ago, there were daily blackouts, and probably every single days a few hundred people got stuck in elevators because of the sudden loss of electricity. We all knew how to deal with the situation, it was part of life. A cable breaking was definitely unusual though. I never heard of it happening to anyone else.
If you're lucky the lift will have detected something wrong and gone into lockdown itself. If you're unlucky it'll start moving with your body halfway through the doorway. It's not incredibly likely to go wrong but the price when it does is too high to risk it.