I really dislike screencasts. I much prefer articles because I can follow them at my own pace. I get usually frustrated quickly with screencasts as, by their nature, they're very slow. Having, to pause, rewind, fast-forward, and then try and figure out at which point in the screencast I am is annoying.
As a developer, I prefer to speed over areas with which I'm already familiar and slow down and focus on parts with which I'm not. Written articles facilitate this so much better than screencasts.