I agree that the creator should use a screen grab that is relevant to the video. There are some that use a screen grab for them mugging for the camera is some contorted facial features. That looks really bad to me. Too much narcissism.
As far as titles, I think a catchy title is OK if it is relevant. Being cheeky with the audience can be fun for those that catch the double meaning or irony.
Tags seem to feed a Boolean type formula so a given viewer can type in some words and the system tries to find matches. I believe the tags should be relevant.