I've used this for as long as I can remember but never realized it was an exploit till I realized I saw almost no one else doing the same. This exploit applies to any battleground where you can mount before the start of the BG (i.e Arathi Basin) I really can only find a concrete use for this in Arathi Basin but it works everywhere else. Basically, before the BG starts run at the gate with the mount like most do to get out first (of course you must stand at the middle of where ever the gate opens just to make sure).
However, by holding down the run forward button W and both mouse keys at the same time(right and left click if you have it bound that way) when the BG starts you will burst through the gate about .5 seconds faster than all others, this may seem insignificant but using this trick means I am 95% of the time first out of the gates on mount with about a 5 foot lead in from of the others, this allows me always to be the first flag capper for ST or whatever flag I go for. This obviously means bonus honor at almost no extra work, this also helps cap bases faster in places like EoS and IoC though no real extra honor to gain from that, just helping the team. Even if not used for honor gains, it still feels really good to be the head of any group rushing out of a BG's gates
So basically-
-go in BG where mounting is available before start
-Run at gate holding down W and double mouse buttons at the same time
-when BG starts you will burst through gate before all other teammates with about a 5 foot lead
-Run for flag to cap and be almost always the first there. No more luck of the draw at who gets ST cap or any other flag cap, mages can blink for almost 100% guaranteed success right before getting to flag.
-I always use chopper but I am almost positive this works with any mount
enjoy!