Learning from books or video is a great way to supplement actual live training. In order for any of the technique to be sharpened in a way where it is applicable against a live, resisting opponent you need training partners to actually apply the techniques with. I personally believe they are a great resource, but in no way can they be realistically expected to work as a replacement for time on the mat or between the ropes.
But if you're looking for something new to try out, books and instructional videos are the best resource when a live source of knowledge is not present.
It doesn't matter if you agree or disagree
... As long as I don't bore you and I spark a moment of thought, my goal is achieved
Queng leon queng tigre ecu tacacut, queca pa? - Pampangan Mandarigma Motto