Wikipedia has this (among other things) to say about art: "Art is the process or product of deliberately arranging elements in a way to affect the senses or emotions." I haven't been able to come up with any counter-examples to refute this definition, so I'll use it.
I see the perception of movies and video games somewhat analogously.
1a. I think a common cultural understanding of video games as playthings (i.e. pacman) which will NOT affect the average audience's emotions in a significant way (other than getting mad when you lose). Clearly there are such games, not only limited to simple, pacman-style stuff, but newer FPS (Halo), RTS (Age of Empires), etc.
1b. Just so, there are movies -- good ones even -- which do not affect the emotions of the average audience in a significant way. Shoot-em-up comes to mind as a good movie that perhaps one wouldn't qualify as art by wiki's definition.
2a. On the flip side, there are video games, which when played in a serious mindset, WILL affect the audience's emotions. FFVII will certainly pass this test, as will Ocarina of Time, and undoubtedly many others.
2b. Once again, just as in movies, we see the same phenomenon. It is possible to watch Romeo and Juliet in a rather cold mindset, and not feel the emotion. However, when watched seriously, the average audience member will likely feel affected emotionally.
3. The other part of the definition is that the elements must be arranged in a deliberate way. Obviously this is the case in both movies and video games as they are created from the ground up by working developers.
4. The way we interact with things does not change whether we call it art. We call art those things which just sit on the wall and don't do anything, but surely we also ascribe the title to architecture (which we can stand on), functional pottery (which we can drink from), and ipods (which we can play music from). What about the way we interact with video games -- specifically the possibility of winning -- makes it any less of an art?
Many video games are art. Really.
