I think this is a pretty good summary overall. I'd like to supplement some things:
Category 1 viewers also contain people who want to vicariously live through someone else and experience their favourite game again for the first time. They tend to stick around only for a specific game, and will move on after the playthrough is over.
Category 2 also contains viewers who watch the streams as a pure entertainment product, more akin to watching a comedian. They're mostly interested in the banter the streamer provides. Many viewers of Northernlion and Jerma fit this description.