It is usually better to be on starboard tack than port tack.  The starting line is at right angles to the wind, and the first mark is on a line drawn from the center of the starting line and at a right angle to it.  The fleet starts into the wind.   It is better to be at the windward end of line. In a perfect start your boat is aimed on the best course to the first mark and is going at full speed.  In the video notice that nearly all the boats are too early and are luffing so that they are not over line at the start.

starboard tack - the boom is on the port side of the boat

port - the left side of the boat

luffing - flapping