Engine braking yes but wrongly done.
If it was given a big handful of throttle before changing down all would be well.
I still think holding it at tick over and craming it into first is too much for the injection to control for a split second.
Even when I downshift for engine braking I give the throttle a little blip just to bring the revs up. Otherwise just dumping the clutch into a lower gear especially at high rpms wouldn't be too good on the clutch right?
In watching the video it sounds very very likely like you just didn't pull the clutch soon enough, engine bogged out and died....
When you were slowing down again later on, as mentioned by someone else, you are in too high of a gear and its forcing the engine to kill itself, the only reason it didn't stall again is because you pulled the clutch at the last moment. Keep those rev's up.