[extrapickles]

That is what is downloaded. Most AAA games are at least 32gb due to the large worlds and the level of detail required.

Everything that can be compressed is compressed, though there still is room for improvement on compressing mocap (motion capture) data. Mocap is done to get characters movements more natural and to help with lip syncing, though it can take up more room than plain video. Prerendered video is not very seamless and does allow player interaction with the scene beyond choose your own adventure type options. This is more of an issue if they want to show the player character as most games have extensive customization of the look of the player character.