A WebmasterWorld thread asks how can an advertiser get his Google video ad to show up in the content network (AdSense). AdWordsAdvisor2 responds to the thread that video ads are CPM based so you have to ensure your CPM bid is high enough to warrant the ad to show up.
The CPM for video ads is based on how many times it appears on the network, not how many times it is actually played. Video ads are definitely live, so you may just need to adjust your CPM to be closer to what you'd expect to pay for an image ad on the same content sites.
It is clear that if someone plays the video, it does not cost more. But what is not clear is does it cost more if they click? I assume so.
My question in the thread is "if your a publisher, you get paid by impression and also by click? Not anything extra if they play it?"
I'll keep you updated on any response.
Update: That was quick, AdWordAdvisor2 responded shortly after saying:
If the ad being displayed is a CPM ad, then the publisher gets paid based on the CPM the advertiser is paying. The publisher won't get any additional revenue if the ad is clicked on as we don't charge the advertiser anything for those clicks.
Forum discussion at WebmasterWorld.