... if you want to learn opening or some sort of defense, books are much better.. believe me, i used to watch video about opening and it's not as deeper as books, in books there are many lines explained and in video, only main line explained..
"... The way I suggest you study this book is to play through the main games once, relatively quickly, and then start playing the variation in actual games. ..." - GM Nigel Davies (2005)
For that sort of activity, isn't a video a plausible choice?
"... the majority of DVDs and videos are best suited for introductions to their subjects and are therefore good teaching tools. If you're looking for comprehensive theory, there's no doubt that you'll usually get quite a bit more from a good book on the subject. But DVDs can contain some surprising gems even in that respect, and in any case they are a good way to add some variety to your chess study." - IM John Watson (2012)
http://theweekinchess.com/john-watson-reviews/chessbase-training-dvds-and-downloads
http://theweekinchess.com/john-watson-reviews/chessbase-dvds-and-downloads-part-2
Using books, a real board, and pieces is Active learning, and is a better way of training.
Videos, and online study is passive and not as efficient.