This disassemble and assemble of BlackBerry Bold 9900 is very different from iFixit type of video. It is very instructional although it states clearly that this video is not intended or should not be used as a guide.
But be careful if you really want to give it a try. From the video on the assembly part, he has missed a part telling users to connect the board to the frame at 05:30 (compare with 03:32). So remember to connect back when you assemble. Here is the video.