YouTube now supports video captions. Captions are uploaded as a separate text file. YouTube also provides automatic translation of these captions into many languages. Web tools for creating caption files are free and easy to use. I recently used overstream to create captions for a docudrama some friends and I made. Making captions takes time and is an art in itself, but technically it is now easy to do.
Even in its “advanced search” page, YouTube doesn’t offer search limited to captioned videos. Search limited to captioned videos would be an easy feature to implement, because the associated caption file readily indicates a captioned video. This search type would be helpful to deaf and hard-of-hearing persons. Moreover, a person’s use of it would provide valuable information for delivering useful ads to that person, e.g. social events and social networks for deaf and hard-of-hearing persons, hearing aids and accessories, etc.
YouTube has a lot of room to improve its revenue. It could implement a premium-paid tier, which might offer videos longer than 10 minutes and better video quality. Its search-choose model with Video ID has much potential. YouTube has added video annotations, which users value and which over time will provide more information for targeting advertisements. The APIs for its video platform will over time provide more information for targeting advertisements. Despite all the hype about Hulu’s revenue, I still think that worse content with higher-value advertising can beat better content with lower-value advertising.
 Videos with captions included within the video stream would be much harder to identify. Unlike the “closed captions” discussed above, these “captured captions” can’t be turned off and on, can’t be automatically translated, and can’t be searched as text. The presence of videos with captured captions doesn’t seem to me to be a good reason for not providing search limited to (closed) captions.