Interesting video. Did the guy record the aircraft flying and later edit in the sound? Sometimes the engine sound doesn't quite match up with what the aircraft is doing (like at the top of the loop). Anyhow, it was still very enjoyable to watch .
airplane sounds will change with plane movement, like when a plane is turning and coming at you it will be a little quieter for a second as exhaust is kinda like blocked. kinda like a jet coming straight at its not loud until it gets closer then passes you.
I believe the film sound is unedited.