Yeah but they could argue that a game is interative while but when watching a program its more like a documentry (some are, some are just senseless violence). Watching something, I imagine is not as bad as killing someone on a game because it is you behind the 'steering wheel'.
This doesn't mean I support this banning of explicit content in games, apperently there is some sort of primitive instinct in over half of us that makes us not want to kill someone. I hardly believe that a serial killer is going to be driven crazy because he played video games during his life, infact I've never heard of a case like this. I think games relaxes you, maybe 'real' (not graphical) images might spark something off.
We don't need these restrictions on games, what we need is responsible parents that are able to decide if something is just too explicit. The people who make these game show age ranges for the parents these should act like guide lines for the children, not be ignored, though shouldn't be to inforced as they are exceptions to children that might be 'grown up' enough to handle it.
Games do not make killers, people do.