Google launched an automatic video captioning service for YouTube videos in an effort to make the visual clips more accessible to deaf people or anyone searching for videos online, but some see advantages for search engine optimization, too.

The machine-generated service will generate English-only captions initially on 13 partner channels. The service combines Google's automatic speech recognition (ASR) technology with the YouTube caption system to offer automatic captions.

"Auto-caps" use the same voice recognition algorithms in Google Voice to automatically generate captions for video, according to Ken Harrenstien, the Google software engineer who created the technology.

The captioning service isn't perfect, but will improve in time, Harrenstien explains in a blog post. Harrenstien, who is deaf, created the technology because "the majority of user-generated video content online is still inaccessible to people like me," he wrote.

The idea of video captioning is not new at YouTube, but the automatic feature could help to further optimize videos for people searching for content across engines and on YouTube. In theory, video scripts should become more optimized by the keywords in the captions. And while it's a great feature to make content more accessible for the deaf, other benefits exist for marketers.

"Having a transcript in the video is huge for SEO," says Andrew Shotland, owner of Local SEO Guide, a SEO in Pleasanton, Calif. "Having targeted text on a page helps the video rank in search engines for specific searches."

Today, very little text from video is being captured on the Web because no one wants to transcribe thousands of videos. Walking through an example, Shotland says if YouTube begins by making one million videos available with automatic video capturing, that adds nearly a million new pages that engines can crawl, index and rank because on those pages are many keywords.

"If we're talking about a plumber video, that page will have words like leaky pipe, city name, change your toilet and many others the publisher may not have added to the written description on YouTube," Shotland says. "The videos will attract search engines even more. I wouldn't be surprised if YouTube's traffic goes through the roof. The video pages will have so much more text they can rank on."

Shotland says if the video transcripts work similar to the embeds, the tag that lets people add the video to their Web site, anyone pulling the YouTube video onto their site can also rank for the text.

The problem, he says, is that spammers will begin grabbing the captioning transcripts and people will begin to see the text appear across the Web. "It will become a spammer's wonderland," Shotland says.

The challenge to index videos has always been the self-tagging architecture, according to Kevin Ryan, chief marketing officer at WebVisible. "In theory, the videos should index more efficiently if they have captions," he says. "It's a big challenge because it's a self-attribution model. The first thing a brand manager wants to do is control where the video is seen, so it's never positioned in a negative light."

Google also announced a feature called Automatic Timing to help video owners add manually created captions to YouTube videos by automatically determining when the words are spoken in the video. Text transcripts are required -- no time codes required -- and Google does the rest.

Video captions made it to I/O videos on Friday. Every English and Spanish video from I/O now has captions that work in YouTube, writes Naomi Bilodeau, manager on the Google development team.