The web video advertising market is going to be a $775 million business in 2007, according to eMarketer. And yet it is a business with more unknowns than one can list. Liz has pointed this out again and again. In fact, even Google folks have said that it is work in progress.

AdAge in its latest issue offers up a few key lessons for brand advertisers and how they can make web video as work. These are tips are based on a recent study of video consumption habits by TNS, done on behalf of AOL and Google.

1. Video-sharing sites are getting a bigger share of visits (77%) versus news sites (55%) and broadcast TV sites (49%). Lesson: Good for YouTube, not so good for old tubes.

2. 43% of those polled want ads to be interactive and clickable. Lesson: Don’t put stupid TV-style commercials that are not actionable.

3. Videos are for sharing. Lesson: Big media, listen to CBS Interactive’s Quincy Smith.

4. 52% want ads to be relevant to them, 46% think they need to be relevant to web site’s content. Lesson: Consumer electronics ads next to people being blown up aren’t going to work. Make your ads contextual, relevant and of course tasteful.

5. Make ads fun if you want attention. Consumers feel annoyed by videos ads today. Lesson: Simple enough.