If it's the minifigure's reflection, it's not a big deal. That's normal.
Now, if it's something that will change frame-to-frame or break the fourth wall, then you've got a problem.
(Be it the computer screen, you, the camera, something else.)
But if it's only reflecting the minifigs or other walls and things, you're fine. And there's not much you can do about it.
Perhaps reducing the amount of light, and then turning up the exposure to compensate? I don't know.
I kinda like contained reflections, as it seems like a more real world, and if it's reflecting the set, it feels less two-walled set-like and more real complete room/location like. So I've never tried to get rid of them.