Add another link to another accessibility value chain! You can use “Advanced Video Search” to find captioned videos on Google. It’s a single checkbox, near the bottom of the search form. This will not only make captioned videos easier to find, but may encourage some videomakers to caption their work — building the culture of accessibility.
Unfortunately, this feature is not yet on YouTube, which is owned by Google — when, please?
A search using this function turns up videos that are NOT captioned, for some reason.