What flyaway?
You launched from under tree cover (?) that blocked GPS reception and the drone flew in atti mode until it got out into the open and acquired a GPS signal.
pretty much took off & had no control of it, got it back after it landed in the shore break.
Your drone was fully controllable at all times, responding to all of your joystick inputs.
It just didn't have the position holding that you get from GPS
got it back after it landed in the shore break.
After YOU landed it in the shore break.
The joystick inputs show you bringing it down with the left stick full down but with three metres to go, also giving some extreme right stick movement.
That wouldn't have been a pretty landing.
More a case of another misleading thread title suggesting not only that these things are likely to "fly away" but that it's a frequent event.
It's thread titles like this that cause inexperienced flyers to believe this.
It would be interesting to compare the number of claimed flyaways against the number of drones that actually did fly away.
I'd suggest it might be something like 100:1