Still in a received medium like film, you feel like things are revealed to you, but never actively discovered.
Potentially inspiring distinction.
So there's a switching of roles: in a film the creator is active. But to feel discovery, the spectator needs to be active. Or feel active?
I almost missed this post! I don't know.
The creator is present, but I'd hesitate to call them active, since film is a passive/received medium. They are definitely active while making the film.
What's active is your imagination, and faculties for judging what is happening. And as QXD-me demonstrated, you can discover connections, if you are actively looking for them (I don't know if I experience film this way, I prefer they wash over me, and that probably affects the kinds of films I--present-I--seek out (mostly foreign language arthouse films.))
But film in this way denies the body. The body is what games can bring to the table; traditional storytelling/idea conveying medium wise. This is why when you say Discovery in the context of games, the mind leaps to unearthing a physical artifact of some kind, or stumbling into a scenic vista.