Sci fi is about not explaining the real science behind what your showing.
IMO stuff should be explained only so far as it is either directly situation relevant or else natural to the dialog. Anything beyond that is clutter. Unfortunately most stuff violates both of these "rules".
It
is important to actually have an explanation though, even if it isn't given to the audience. Part of that is that it's just good writing practice, and part is that it's kind of a corollary to the definition of sci-fi: science is inherently about things which can be understood, magic is inherently about things which can't.
Granted, the distinction is blurry from a scientifically illiterate point of view. To most people who use cell phones (for example), cellphones are only "not magic" for arbitrary reasons, since they don't know the first thing about what's inside or how it works. But as Drachenklinge pointed out, subjective POV is not a logically stable way of defining things.
One advantage visual media has over print is that it's high bandwidth, enabling one to cram in all kinds of incidental stuff (like technical explanations) in without diverting away from the central focus.
Take Riddick's eyes in
Pitch Black as an example of how to things right:
On the one hand, the nature of the mods to his eyes are never gone into beyond the bit that's plot relevant (he can see in the dark), and a smidge of character development (he bribed a prison doctor to do it, so he'd have a survival advantage in the gloomy prison where he was kept). Only the bare dramatic essentials. No wasting time with beside-the-point verbal exposition or cutting away to beside-the-point scenic exposition.
On the other hand, the visual effect for his "eye shine" tells you quite a lot about the nature of the mods, if you're technically minded. It's clear that the people who designed it actually put some thought into how his eyes were altered and how to show that. But to those who aren't technically minded it just plain looks cool, and visually marks his eyes as being different.
The tech exposition runs parallel to the story rather than being intercut, as it would have to be in a book, and it serves double duty as both exposition and cool visuals. It's there for those who are interested, and those who aren't will never even notice it, either directly or as clutter. Elegant and efficient.