Yeah he wasn't the quickest but that part can easily be done a lot quicker. I was originally going through the middle at the start but I found it a lot easier to go the way on the video. It makes the flashbang more effective throwing it from the right as well, and you less likely to get shot by anyone else.
The 2nd room downstairs I went on the right, flashbanged over and rush in front of the nearest seats on the right, usually there's a bloke standing there so I just knifed him, then your team will come and shoot the ones coming down the stairs whilst you reload or whatever. That method got me past the 1st floor every time.
