With iClone’s major sci-fi competition imminent, I thought I’d do a quick round-up of space-sims which might help round out your iClone footage. Freespace 2 and the Infinity combat prototype seem like the ones with the most potential…
Orbiter : space flight simulator. Free British 3D space sim from 2006.

Freespace 2, a free open-source 3D game from 2000. I’ve played it and its portrayal of space still looks quite pretty on a big PC widescreen, if you judge it by the standards of the time. It’s possible to get many interface elements off the screen, and the retro look to the spacecraft and space stations could blend well if you’re not trying to disguise iClone’s low-poly look. Worth a look, if you’re thinking about combining iClone with some gameplay footage.

Vega Strike. Still only half-built but playable, an open-source game. Definitely not as pretty as Eve or X3 (see below). Between the two, I’d say Freespace 2 is probably the better choice and is easier for a novice to actually play enough to get to some interesting places in the game world.

Evochron Legends (demo). Nice indie community-powered single-player Elite-alike, using a procedural engine. Has a seamless planet-fall (i.e.: descend from orbit to land on a planet, all in a single sequence) but is otherwise several years behind the visual lusciousness of Eve and X3 (see below). As with all modern space-sims, there’s a ludicrously steep learning-curve involved, and don’t forget to pack your motion-sickness pills.

X3: Terran Conflict (single-player) and EVE Online (multiplayer) are generally considered the cream of the retail crop of PC space sims, and both look fabulous if you can peer through the mass of interface elements — but it’ll take you 50 hours to get into them, and the companies involved may well object to having their games used in competition movies? The same goes doubly for Mass Effect and most other recent major retail games set in space.

ABOVE: EVE Online — as with most retail space sims, there’s also a lot of micro-management interface cruft cluttering up the screen. And as you can see here, planets are often not optically correct — they looks “bulged” from certain angles.
You might get away with “fair use” with the poorly-received 2006 game Darkstar One. They’d probably be flattered that anyone is still playing it. The game has what is probably the most beginner-friendly learning curve of the modern space-sims and a demo.

Infinity combat prototype 2.2. 2007 community release of a playable visuals demo of a forthcoming (eventually) indie/fan-project game. Very nice visuals, it can apparently clear almost all interface clutter off the screen, and it can already do multiplayer. Definitely looks like one to test, I’d say.

There’s also good-looking free software such as Stellarium which is a free open-source planetarium. Visually it’s quite attractive, and might be useful if you need visuals for an info-graphic video clip (e.g. script: “we need to intercept the rogue comet here!” — /she points to a spot on an interactive star-map/).
Mars in Google Earth, based on NASA photos and mapping, might also be useful. Also the NASA photographs and the Hubble space observatory photographs.