I attached the 2x2 blocks the same way as stated in the book, with glue and screws, and the shelf brackets held up fine at the angle. The main thing keeping the tv from sliding back is the upper back panel, but I also put in a few small wood blocks on the shelf, snug against the back of the tv, to make sure it was secure and wouldn't slide at all. I'm pretty sure the extra blocks weren't needed and were added as an after thought when the cab was already complete, but I figured its better to be safe then sorry.