I see the white 19 form a ruck and drive the gold player off the ball.
I'd say the ruck has ended because the ball is clear of the players that formed the ruck.
Show me where it says that in Law. All I can find is....
[LAWS]ENDING A RUCK
18. The ruck ends and play continues when the ball leaves the ruck or when the ball in the ruck is on or over the goal line.[/LAWS]
The "players that formed the ruck" are not mentioned.
Given your interpretation, what happens if another player binds onto a player who formed the ruck. If the ball then moves behind/beyond the feet of the player who formed it, but remains in front of the feet of the player who just joined, then your interpretation above would mean that the ball has left the ruck!
If, as WR appear to, you think there is still a ruck (whose participants are now on the ground) then the white offside line is formed by White 19, and White 18 remains behind White 19. There are still tacklers on the ground but we went from tackle phase to ruck phase already, so no TWOL.
Firstly, once a ruck its formed, it does not matter if all the players have gone off their feet - the ruck remains a ruck until the ball has left it.
Second, I completely disagree with the bolded statement.
The white offside line is the white line I have drawn past the gold player's right shoulder
The gold offside line is the gold line I have drawn behind the players hindmost to the gold side
[LAWS]OFFSIDE AT A RUCK
4. Each team has an offside line that runs parallel to the goal line through the hindmost point of
any ruck participant. If that point is on or behind the goal line, the offside line for that team is the goal line.[/LAWS]
I know it used to say hindmost foot of the hindmost team mate, but not any more - that law has changed.
I don't think this is a great clip for law 15.7!
I agree. With anything upwards of 150 tackle/rucks per game, you would think that one game out to be enough to give a few better examples to choose from