Both. Each has their strong point, I usually divide them into:
* Directed learning by reading.
* Undirected learning by videos.
That is, if I know what I want to learn then I can usually go straight to it in books. If I just have a general fuzzy idea then videos tend to offer a higher level view that can help me to clarify my understanding.
I think videos are a poor medium for highly detailed learning. If you're looking for specific information then a book is much more easier to skim than a video is, it's not a good prospect to spend time watching a video to discovered that only 1% of the content was novel and relevant.
* Directed learning by reading.
* Undirected learning by videos.
That is, if I know what I want to learn then I can usually go straight to it in books. If I just have a general fuzzy idea then videos tend to offer a higher level view that can help me to clarify my understanding.
I think videos are a poor medium for highly detailed learning. If you're looking for specific information then a book is much more easier to skim than a video is, it's not a good prospect to spend time watching a video to discovered that only 1% of the content was novel and relevant.