Well, hang on, we're setting the value with innerHTML, so we should probably be reading it with innerHTML.
https://github.com/videojs/video.js/pull/638/files#L1L743

Otherwise we'll get different results if there's any child nodes.
> For other node types, textContent returns the concatenation of the textContent attribute value of every child node, excluding comments and processing instruction nodes.

The fallback message isn't meant to be limited to just text, in fact the actual default message has links.