While standard ad units are the most commonly used, most ad networks accept all major rich media formats and are increasingly offering a range of video advertising options.

Despite rich media being readily available on networks, there are a few issues to consider:

• With rich media advertising, an additional provider is involved, requiring additional time to build the creative assets. This is for marketers who want to push the creative envelope.
• With rich media each provider typically has its own serving fee, which will increase the overall media cost.
• Dependent on the rich media provider and its relationship with the sites on the network, some network publishers may not accept certain features or sizes on their sites, potentially limiting the available inventory.

The leading use of video on networks is in-page video, which is delivered within standard display ad units, similar to rich media banners. Transitional video refers to video campaigns distributed as interstitials, which play the ads between pages, while a user moves from page to page. In-stream advertising, also known as pre-roll, mid-roll, or post-roll, is inserted within a video player window before, during or after streamed content.

In-stream inventory within premium content is in short supply across networks, since much of the available inventory is user supplied. (In an ideal world, networks offering video should classify content into tiers so an advertiser can make an informed decision about what video inventory to purchase.)