Eliska,
There could quite easily be a case for humans being more 'suggestible' when being passively absorbed in watching a film. The metabolism slows, the mind is soft - and impressionable.
I dont know - as Stefano says we should rely on research - and afaik there is none conclusive.
I've done my own research though, having always been a gamer.
I know this is more about the effects on children - and I'm all for parents observing the Age Rating, but I've played the most violent, materialistic, Gory, shocking games out there - & I'm a peaceful, vegetarian - I try in every way I can not to encroach upon the freedoms of any individual man, woman or beast !
Because - video games - are just a little part of life, just a movies are just movies, music is just music - games are just games ;-)
Havn't there been times when convicted murderers have sited particular songs/tracks as triggering their crimes ? - but I think we can all agree - its not the fault of the songs !