In Welsh classes in school we used to watch Gogs [0] but it was never once explained to us that it comes from Goggledd, nor do I remember learning that word.
Edit: Having just watched a couple of minutes of the clip, it appears that it's independent of language (like Mr. Bean) so I'm not sure why we used to watch it in Welsh classes, but it probably goes someway to explaining why I don't know many reasonable basic words in Welsh.
[0]: https://www.youtube.com/watch?v=E8VvGbHNBww
Edit: Having just watched a couple of minutes of the clip, it appears that it's independent of language (like Mr. Bean) so I'm not sure why we used to watch it in Welsh classes, but it probably goes someway to explaining why I don't know many reasonable basic words in Welsh.