Here's why: a captive audience.
The video ad viewing results shared today by TapJoy go a long way to proving this. While TapJoy ads aren't representative of most video ad networks, they are predicting where the market is going:
For a telecom campaign, for instance, the Tapjoy videos produced a 48% higher recall, vs. 22% for TV, and the mobile campaign generated 25% brand likeability vs. 11% for the TV spots. Source: MediaPostIf a viewer wants to watch a video badly enough and they are forced to watch pre-roll, they will. And because they know the length, they know there's only one ad, and they know the won't be bothered again, they'll do it. They've actually been doing it, and watching pre-roll video ads will continue to outpace TV for engagement, ad recall and brand recognition simply because they can't skip through it, and it's short enough where they won't try to multi-task to something else. The format, the form, and the length make these ads truly make users watch them.
Now, not all videos are of equal consumer value, and the views on a single average video are nowhere near the volume of a single TV show. But this is clearly quality over quantity right now. But, equal quantity is just a matter of time as the walls breakdown between interent-based and cable-based video distribution.
Consumers implicitly understand this ad tradeoff now - "I watch a video ad (which I might even be interested in), I get the content I want to see".
As long as publishers / advertisers don't start loading more than one 20-30 second clip, and the video ads are contextually or personally relevant to me, this tradeoff really works out. Video ads are only going to get more engaging, and that's better for consumers and brands alike.