Those going for the Goat Roped achievement (
) as well as this one (the goat roped achievement is for completing the halo combat evolved anniversary on legendary in under three hours
) i followed this guy's video. Also, when you jump off of the bridge, I found it easier to jump off of the left side instead of the right like in the video. When you do this, no enemies will spawn past the bridge and makes it very easy. My time was around ten minutes but as you can see in the video it is possible to speed run in under seven minutes.
Make sure to get practice with jumping off the bridge because, although not impossible, it is difficult.
Credit for Pidgeonator for making this impressive video. Also, in order to get the Goat Roped achievement, you have to complete each level in under 18 minutes, so this method gives a lot of leeway time.
Last Video: credit to Clumpsy Jimmy
If you play co-op, you can kill your second player then do the jump. Even if you miss, sometimes your second player will respawn down on the second cliff. This makes it way easier.