According to the video_games page, it is to be used whenever an image shows "a video game, or characters from video games." Besides the oddity of those two elements sharing a tag, video games are the only ones to receive such a tag. To wit, cartoon and movie are defunct, anime is unhelpfully vague but seems to only refer to characters drawn in an anime style (maybe?), and comic_book and book only apply when a physical book is seen. Even if you want to argue that there are enough gaming-based images to warrant the tag, I don't see why they're the only ones to get the special treatment. Beyond that, is anyone actually searching for "video_games" expecting to see images of random characters without a physical video game in sight? Personally, I'd like to see the category retooled to be more in line with the book tags.
Updated by O16