Hum. I just finished there - well not finished - i did the main objective but i still need to figure out some of the puzzles to loot the extras. I did htat one and it took a while but i'm not sure how to give a hint - also there is one upstairs you have to get to actually complete the main objective. the one with the wall wasn't obvious and took me the longest. Btw i'm having trouble following the video but where are you stuck ? I'm going back there in a few hours to work on some more of the chests.