Adobe, Mozilla, Opera and a variety of other industry players kicked off the Google I/O conference Wednesday pledging their devotion to HTML5, and support for the royalty-free VP8 codec and WebM format available free to anyone. The video format, billed as a technology that will revolutionize online video, got a nod from the magazine Sports Illustrated. But it’s getting nods from advertising and marketing agencies, too.

HTML5 gives advertisers multiplatform support. The campaign will play back on an iPad, iPhone, Android phone, desktop and Internet-enabled televisions. It also enables developers to create online games. Agencies won’t need to develop 19 formats to support just as many campaigns. If the format takes off and is widely adopted, it will enable campaigns to easily work across devices.

Some devices do not support Flash or Silverlight today. Apple, however, does support a version of the new codec called H264. Today, HTML5 on YouTube is a TestTube experiment. It does not support ads at this time.

What’s in it for publishers? Evidently, support for paid-content subscription models online. Terry McDonell, editor at Sports Illustrated, demonstrated a magazine application in development that featured video running within a frame of text. It looks similar to a magazine with rich video running inside the page where you might see a still photo. Adding an addendum to the famous Field of Dreams quote “if you build it they will come,” McDonell says the online publication must be built open, well-edited, searchable, social, and available everywhere. “If we do that we can charge for it,” he says.

Despite the obvious reasons to rejoice, some industry executives believe the advertising and marketing industries can expect to experience little chaos near-term, before things settle down. “We’re building towers on shifting sand,” says David Dudas, vice president of product development at Sorenson Media, which pioneered codecs that provide the backbone for Apple QuickTime, Macromedia, now Adobe, Flash and YouTube, along with the encoding software for high-quality online video. “Agencies will need to learn how to develop around the format to take advantage of it. Frankly, I think that will become a challenge because everything changes so rapidly,” says Dudas.

This alternative to Flash should cut development costs for agencies trying to create and manage campaigns for clients, according to Peter Csathy, chief executive officer at Sorenson Media. The format will provide instantaneous playback and low power consumption and become much more efficient, he says. This matters as agencies try to deliver campaigns to everyone everywhere on a variety of platforms.