It appears that YouTube catalogues the videos according to the tags put on by the people who upload them. That way of doing it as a lot of good points - but it means that there is likley to be some inconsistency, and it maynbe hard to find clips thta haven't got an obvious tag (for example the ones I linked in my earlier post).

It would in principle be possible to do that outside YouTube itself, and in a way that would ensure consistency and easy access, and to carry such an index on the Mudcat. But it would be likely to involve a lot of work setting it up, though it might be possible to spread the load of keeping it going once it had been set up.