I checked out the possible chest location I mentioned in the new area and it's legit (no chest but seems right for one). Took me about ten to 15 minutes to get up the footings he mentions and it's pretty frustrating slipping down again and again so thought I'd share one way I found to do it. Facing the end of the alcove use glide to go up and Left, then a quick right then back left (to avoid ledge above head), forwards, left and done. Don't finish glide abruptly or you will fall too quickly towards the ledge and slip back down. Found it harder than the vanishing rocks first time, but once you know where to jump it's pretty easy. Has to be a chest here, just have to figure out the requirement!

UPDATE - Me and lancer had a quick look round the new area and found that it leads to the Templar area, missing out the vanishing rocks, and gives you a vantage point which one person even claims to have soloed the Templar this way. I'm hoping this new area is meant for more than just a bypass and a vantage point, and am keen to search for a chest here next time we raid. If you read the recent comments for the third video I linked, one guy has an idea where a chest might spawn in this new area: "There's a possible chest spawn point I found as well. At the bridge you crossed at 1:48-1:52, put your back to the wall while standing on the bridge and you'll see a small tunnel straight ahead of you (across the drop area). If you enter it, it's only a few feet deep, but if you look up from there, you'll see footings you can scale the wall with to come into another short hall that leads to a dead end. That's where I think the chest will spawn in this area." Someone claimed that when they did it on hard and no one died, with none of the plates ever being taken, that a chest spawned. Another that there's a door that they couldn't open. Others also say it's just an alternate route, but here's hoping.