I disagree with the application of the rule to the animation in this one. I would say that both red & green have entered the two boat length zone. However I can't find anywhere in the rules where it discusses what part of a boat has to enter the two boat length circle. Hence I would conclude that it is (similarly to overlap and finishing) at the point when her hull or equipment in normal position first enter the two boat length zone. In the animation the sails of both boats in normal position have entered the circle.