We've been evangelising about the power of captions and subtitles for SEO for a long time now. A closed caption file is a form of text file, after all, and it stands to reason that storing what is effectively a text transcript of your video on your site is likely to make the video content more accessible to search engines. We've seen many of our clients' videos rise up the search listings substantially after being captioned, so we've been convinced of the theory, and our clients have been more than happy.

But it's been hard to turn up concrete evidence to prove that captions and subtitles affect SEO... until now. In the last few months it's become clear that YouTube's search results are visibly affected by the caption and subtitle tracks on certain videos, and if you don't believe us take a peek at this image.

Yesterday I made a fairly standard approach to a potential client, asking whether they’d be interested in subtitles or captions for their video content. We’re talking about an organisation set up by the UK government, with many dozens of videos on their site, so I figured maybe they’d be interested. At worst I’d get one of the usual reasons for not wanting to talk to me – worldwide recession, not a priority, yada yada yada. But no, this time I heard a new one.