With the popularity of online video advertising on the rise, media buyers are faced with large variations in pricing and options to decipher. Pre-roll video ads can run anywhere from CPMs under $10 to $50 CPMs - and if buyers aren't careful, they can end up paying for ineffective ads.

Some industry observers are pointing out that video ad networks are deliberately inflating ad impression numbers by running video ads that begin automatically when a user lands on a site, with those ads sometimes below the fold where a visitor is unlikely to see them, writes Adweek (via MediaBuyerPlanner). Ads for brands like Snickers and Sprite recently ran at the bottom of Puff.com and Qj.net, which was likely not what the brands had expected when they made the buy.

Video ad network Tremor Media, which served the Snickers and Sprite ads, says it has never allowed below-the-fold ads, but admits that its partners don’t always play by the rules. Adam Kasper, SVP and Director of digital media at MPG/Media Contacts, adds that some networks manage their partners poorly.

Such practices make it important for brands to monitor their buys, but that is not always an easy thing to do, when networks like Tremor offer a variety of options across thousands of sites. Buyers who want to monitor where and how the ads are running must either do so manually or bring in a tracking vendor, which is expensive.

More than two-thirds (67%) of online Americans now report that they have streamed or downloaded digital video content from the internet, and most feel it's reasonable to watch embedded ads in online TV and movies if the desired video content remains free-of-charge, according to data from Ipsos MediaCT’s most recent MOTION study.

National digital/online media, which includes rich media, online video, classifieds, email, display and mobile, is expected to decline 11.1% this year, according to Magna.