Ok, so I had intentions of filming the teleporting elite trick mentioned by CanadianMonk3y (http://carnage.bungie.org/haloforum/halo.forum.pl?read=99054)
finally got around to it, turned into more of a filming spree (I apologise for that) The banshee just ran me down one too many times and I got a little to in to hurting the banshee in more than one way... The one movie I would suggest watching is: "Movie: Elite Banshee Switch" if you don't want to watch them all... But the first movie is small and shows the basic trick...
When crossing the loading zone to transport the third banshee back to the beginning of the level, I came accross something weird that I had never seen before in the level, it's worth a quick look because it is kinda strange...