This is a great video to illustrate the tacking and right of way rules.

My experience is that sailors believe that so long as they get their boat around onto starboard that they have tacked and the burden is now on port. (period end of story)

They forget that they have to give room and opportunity to port (B) to avoid them. They don't instantly receive a get out of jail free card by sitting there on starboard. (Back in the day... you would see sailors grab the boom and push it to starboard and holler starboard (ha ha....) The rules have changed ...

What I see is similar to Eric..... Port (B) went into max avoid while starboard (A) had no rights and was tacking. This avoid collision was before starboard would have acquired rights... They (A) acquire rights on starboard ONLY AFTER the room and opportunity to avoid a collision requirement is met.

I look at the video and see that Port could do nothing more (The fleet knows that the boats don't bear off... the bows dig with rig that far forward and the rudders come out of the water and stall.... game over)

Room and Opportunity is the key phrase here... Looking at the video... do you think that port was not doing all they could to avoid the collision? Do you think they were late to respond.... IE after (A) is now sitting there on starboard with Port (B) missing their opportunity to avoid a collision.

Starboard (A) took a chance that they would complete the tack and get moving AND that port had room and opportunity to avoid.... They screwed up on both factors.

Imagine the protest without the video or witness's (who's accounts as to time and distance will certainly differ)