Is this a start?

If so there is no entitlement to mark-room (Preamble to Section C)

Edit:  ok, sorry looking at the wrong video.

That is not a start - just a mark rounding - in my view this is 15 had mark room rights so 51 should be DSQ. 

From the moment that 51 did her last gybe, 15 was inside overlapped and had rights.

And also broke Rule 14. DSQ.

Agree with Phil and Jeff.  When 51 gybes there was an overlap (last point of certainty).  I cannot be certain that the overlap was broken, but when 15 also gybed there was definitely an overlap.  This supports the inference that the overlap wasn't broken.

Thank you gentlemen. Confirmed my thoughts. Will be used as an education piece at our next meet.

Hi Phil,
I would agree that 51 was outside the 4 BL zone when 15 became overlapped inside, and 15 is entitled to mark room.  In these conditions, I would expect the boats to be covering a little more than 1 boat length per second (ie >1m/s) and from the moment of overlap, it took them at least 4 seconds to reach the mark.
  

Is that a Duck?  The leeward mark?  I've seen several mark shapes  - cylinders, tetrahedrons, tomatoes, hippity-hops.  That is my first duck.

Yes that is a Duck we have been using it for a few years and have just recently add a bear .We sail for fun not sheep Stations

Classic example of a competitor wanting to go wide around the mark and another one on the shorter route inside. Once you gybe you create an overlap all the way to China ! Hence the inside boat has Mark-Room rights as long as the overlap was established outside the zone! Which is clearly the case.  Nice RC racing by the way ! Lovely Marks !

The red line is 51's transom extended out.  15 is clearly inside of 51 and has rights.

Also, just before 51 called for room, she gybed onto port inside of the 4 BL circle, so she would have fouled 15 had she continued to head up to try to close the door.