I'll also recommend Brian Green's novels. I still remember the pop in my brain when I finaly managed to fully grasp relativety. He also paints a pretty clear picture about the what and what-nots of everything quantum, even if you find yourself backtracking.
As far as string theory goes, I really wish they would have called it string model because the patchwork of additions and suppositions leaves this theory hanging by a thread IMO.
Nevertheless I owe a lot to Dr. Green and would recommend his books to anyone interested in physics not just string theory!
Oh and forget the videos, it's like comparing tolkien/potter to their films releases: a lot of shine, but there is just no intimacy.