Just entirely in terms of personal preference, I generally stick with default lighting in Rock Raiders precisely because of the mood and atmosphere. Sometimes, not being able to see everything so brightly and so clearly is an intentional part of the game's presentation. For example, you can certainly play Half-Life 2 or Black Mesa with "fullbright" set to 1, making everything bright and clear to the viewer, but it really loses a lot (see the screenshot comparison here). The darkness in Rock Raiders does make you feel that much more isolated in the depths of an alien planet, like you're playing a Metroid game.
True, it's been years since I've played Rock Raiders so I don't remember how different it looks or feels with increased lighting. But, I do remember how cool it looked when your cursor was not near a building/vehicle, and therefore the lights on said building/vehicle were allowed to stand out and shine through the darkness. Small touches of detail like that go a long way, in my opinion.
I suppose another factor is the purpose of these videos. If you want to present Rock Raiders as-is to the viewer, "This is what the game is and this is what it's like", I'd stick with default lighting. But, if you did want to specifically showcase the game in such a way that full lighting would specifically be beneficial to the presentation (say, showing off units that are spread out across the cavern rather than all in one place where they can be highlighted by the cursor), then I suppose increased lighting could work. Alternatively, there's nothing to stop you from going to the OPTIONS![/chief] menu and switching between default and maximum lighting whenever you please. That way, you could turn on full brightness when you need it and keep it off for the rest of the game.
Just my two ore.