Video can be great for describing certain concepts. Like illustrating the relationship between pi and a co/sine wave. Or anything related to animation, physics, etc. in code.
Video can also be useful for learning how to setup a development environment, to show how to use developer tools in FF/Webkit, setup an Xcode project, etc. Instances where a student needs to navigate a complex UI to begin the work of actually coding.
For coding there's many problems with video. One issue is bandwidth: text can be scanned and consumed very quickly. Text can be given a hierarchical structure that a student can jump between, which makes it easier to understand complex relationships between concepts. Video is linear. Code is not. Code has a relational and web-like structure that is more accurately represented by hypertext.