The obvious answer would be “offline rendering”.
Even if the non-interactivity of pre-rendered video weren’t an issue, games as a category can’t afford to pre-render more than the occasional cutscene here or there: a typical modern game is much longer than a typical modern movie—typically by at least one order of magnitude, i.e. 15 to 20 hours of gameplay, and the storyline often branches as well. In terms of dollars grossed per hours rendered, games simply can’t afford to keep up. Thus, the rise of real-time hardware 3D rendering in both PC gaming and console gaming.
I wasn’t even considering the possibility of static images in video games, because static images aren’t generally considered to count in modern video games. The world doesn’t want another Myst game, and I can only imagine one other instance in a game where photorealistic, non-uncanny static images constitute the bulk of the gameplay: some sort of a dialog tree / disguised puzzle game where one or more still characters’ faces changed in reaction to your dialog choices (i.e. something along the lines of a Japanese-style dating sim).