If I had to pick one, I would give a slight edge to short, concise screencasts. With audio of the person dictacting what is happening in the video. I think it's a good way to pick up valuable insights that may not have been presented in more of a "step-by-step" tutorial.
But I think I tend to absorb information better when written, accompanied by relevant screenshots, on an easy-to-read website. Where I can easily copy and paste code and try it out on my own while I'm reading, without having to rewind if I miss something while following along.
For me, it ultimately to do with style. I'm going to have just as short of an attention span on a boring 30-minute long video as I would with a boring tutorial that takes 30 minutes to read.
If the material is concise and well-organized, it doesn't matter so much to me.
What are your thoughts?