Perhaps the most significant part of the HTML5 spec is the ability of video to be run natively in the browser. Much like native apps on the iPhone, native video enables a whole new level of interaction, emotions, and analytics for online video advertising.
As demoed recently by Apple's Steve Jobs, ads on computers are about to undergo significant changes. Everything from tracking to animation will be altered in the process (for the better). Ad agencies & video ad networks will be able to provide real-time, interactive experiences that aren't limited by plug-ins.
Here are some of the ways ads are going to change:
Real-time, in-depth analytics. Analytics for video is often separated from web analytics, but with the HTML5 video tag, this will no longer be the case. Playing video natively in the browser allows for a whole new level of analysis, including all video actions, engagement, % complete and view through rate (VTR) being trackable and linkable to standard web analytics such as funnels and conversion rates. For advertisers, this will make it easier to measure the effectiveness of video ads.
Measured interaction. Being able to engage and interact with a video introduces a whole new experience for the user (and publisher). The ability to play video natively in the browser opens a new world for those posting video online while allowing them to gain valuable feedback from viewers. While this scenario above has always been possible on the web to some degree, the difference now is that it will be seamless and ubiquitous (no downloading software, plug-ins or annoying interruptions). A user will be able to watch a video, interact with an ad, buy a product, and then return to the exact spot in the video without interruption.
All's well that sells well. HTML5 is probably the most significant update for all kinds of rich media. Especially for video, which has long been awkwardly implemented in browsers, fortunately the path looks clear for the future of in-browser video. As any good advertiser knows, videos create emotion & emotions mean sales.