Whether or not you should write "unshootable" stuff is more or less a solved problem. But what qualifies as "unshootable"?
A common example is action lines that describe what a character is thinking, rather than what they're doing. But there's a fine, fine line between something a character is thinking or remembering, and something they're feeling. Thoughts don't show on a person's face, but feelings do.
Fantastic Four, though a crappy story, is at least well-styled. To wit:
- So it's not my money you want. It's my toys... Tell me: if NASA doesn't trust you, why should I?
- Victor is a step ahead. Reed pauses, thrown for a beat. Ben wakes up, suspicious. Victor notices. He notices everything.
- "Victor is a step ahead." On its face, this is describing the momentary power relationship between Victor and Reed. How do you "shoot" that? Well, you don't, not explicitly: the way this manifests itself on-screen is in Victor's mien as he says the line. It's more or less information for the actor's sake, so that he knows that Victor is delivering this line with a bit of relish in the fact that he's got one up on Reed. (Of course, the actor always has the right to make choices, but I entirely reject the idea that the writer should never write anything that indicates how a line should be read.)
- "Reed pauses, thrown for a beat." This is a little easier to shoot, it would seem; someone pausing is definitely shootable. But it's not just Reed pausing; he's also feeling disoriented by Victor unexpectedly knowing what Reed's after. Disorientation can show on an actor's face. It's the same thing, a suggestion to the actor.
- "Ben wakes up, suspicious." Same deal. Ben Grimm is standing there, not really paying too close attention. But when Victor says his line, Ben realizes, Waitaminit, something's going on here that I'm not clued in to. This could manifest itself as Ben tilting his head up sharply, his eyes focusing more closely on Victor, his body tensing as the fight-or-flight instinct kicks in.
- "Victor notices. He notices everything." This one is actually sort of a meta-instruction, referring to the previous three sentences. It tells us that Victor is aware of Reed and Ben's reactions, and what they mean. Again, this ends up functioning as a suggestion for the actor, that Victor maybe glances at Reed and Ben in turn, soaking up more information. And it's also a detail about Victor in general; he's always noticing everything that's going on with people he's interacting with.
Memories are what people usually mean when they say, "Don't write unshootable stuff." More specifically, memories of things the audience didn't see happen. If a character remembers something about their childhood, the best you can do to shoot that information is to have the actor express an emotion that relates to it. Maybe he smiles fondly, or grimaces sadly, in either case his eyes unfocused, staring off into space. But unless we have some other way of knowing what he's reminiscing about, he could just as easily be remembering the awesome steak sandwich he had for lunch, or regretting the chocolate milkshake that's giving him gas.
Sometimes, you can write something that would be unshootable, if you wrote it a little differently. For example, describing a woman as "still riding high off the glory of winning Miss Alabama ten years ago." How does her facial expression or posture tell us that she won the Miss Alabama pageant (as opposed to Miss Georgia, or Miss Issippi)? The only way to do it would be to either show a photo or newspaper clipping on her dresser, or a flashback, or have someone bring it up in dialogue -- and if you're going to do that, why bother putting it into the action line?
On the other hand, imagine describing her as "the kind of woman who won beauty contests when she was younger." A decent actress's demeanor can easily demonstrate that kind of history.
Okay, that's enough blathering for today. Back to writing.