"If a boat obtained an inside overlap from clear astern and, from the time the overlap began, the outside boat has been unable to give mark-room, she is not required to give it."
Based on the video that is about as clear as the day is long. And yes, the astern boat did clearly bounce off Karl's boat, immediately changing course and hitting the N20 boat. Should have staying high and just running over the mark would have been proper.
Rule 18 doesn't apply at starting marks. Read the preamble to Section C.
