I'd spend more time on the written docs, and I definitely wouldn't replace written docs with screencasts. Especially for how-to documentation, people want to skim first, then go back and follow the steps themselves, and the latter part is more difficult with a screencast.

As a side note, I only really watch screencasts for stuff that I'm already very interested in. Watching a video means plugging in/finding headphones if I'm in the office and making a commitment of a couple of minutes.