Online video ads cost advertisers substantially more than display or text advertising, but prices might drop as its novelty fades, says a new report by eMarketer.

Citing research by Bain and Company for the Interactive Advertising Bureau (IAB), the eMarketer "Video Advertising Online: Spending and Pricing" report says the average video CPM among seven Web publishers surveyed was $43, about three times the average display ad CPM of $15.

The study says U.S. spending on online video ads will hit about $5.8 billion by 2013. It currently stands at about $505 million. The researchers also predict online video ad spending will constitute almost 10 percent of the total spent on online advertising by 2013. It currently constitutes about 2 percent.

The report notes that some premium sites are charging a CPM approaching $100. It notes the Associated Press found that TV networks are charging higher CPMs for online video ads than for over-the-airwaves ads. "Where the average for a primetime show is about $25," experts say the online rate ranges between $35 to $50 per thousand.

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