In a long-anticipated and legitimizing move, the Interactive Advertising Bureau (IAB) today released its new approved video advertising guidelines, agreed upon by some 145 video sites and advertising companies.

Like those for other forms of online advertising, the guidelines should make new forms of video advertising compatible between sites, so publishers and advertisers have an easier time working together. They also protect consumers, to some extent, from obnoxious new styles of video advertising that would not be compliant.

The headliner format is the new kid on the block, overlaid video advertising (formally called “non-linear video ad formats”). Also included are the more traditional formats: “linear” video ads, a.k.a. pre-rolls, mid-rolls, and post-rolls, as well as companion ads, or ones that surround a video player.

One thing that really matters to users is duration. Linear ads can be no longer than 30 seconds, and overlays or bugs can be no longer than 15 seconds. But you can’t fast-forward through linear ads, and overlays can take up to one-fifth of the screen plus 20 more vertical pixels for “drop shadows, flying sparks, etc.”