Kudos to MSN for evolving the pre-roll format by announcing they'll only insert at the beginning of a session and then only every three minutes. This "capping" policy is yet another effort to make pre-rolls more digestible.
Like it or not, pre-rolls are here to stay. They're an easy re-use of expensive creative. They're straightforward to see, because they're easily understandable by buyers. And while few viewers will admit they want ads, with better targeting, they're actually a familiar experience for viewers and could be useful.
Everyone I talk to agrees. Especially in the broadcast community. So while overlays and other formats will make inroads on pre-roll's turf, significant attention should be focused on improving the pre-roll experience and effectiveness, because that's where a lot of the ad dollars will remain.
So moves like MSN's are welcome. The question of course is, what effect does this capping policy have on their inventory and economics? The question of fleshing out the ad-based broadband video business model persists. If MSN can demonstrate viewership and satisfaction increase, and the economics work, I expect other aggregators and providers will experiment with this approach as well.