I would suggest that you charge the client for doing the artwork and great menus. Afterall, if you didn’t do it, the client would have to hire a graphic artist to do it.
As for putting your name on the media, it’s a good thing to get the client’s permission first, after all, it is their project. I used to put a three second black video clips after the clients video and then my logo at the tail end.
You might consider trading your graphics expertise for exposure on the client’s media.
Cheers.