It’s the last half a minute or so of the footage that’s the most interesting, though, as Tolkien reflects on the possibility of others picking up his languages:

I wouldn’t mind other people knowing it, and enjoying it, but I didn’t really want to—like some people who have been equally inventive in language have done—and sort of make cults and have people all speaking it together. No, I don’t desire to go and have afternoons talking Elvish to chaps. For one thing, of course, Elvish is too complicated, I’ve never finished making it!

That’s not stopped thousands of people from trying ever since, Professor Tolkien!