If you want to see the spines of the nomad ship,, then try docking on a planet like Toledo. Most of the time, you will see the spines show through when you are entering or leaving. As to why the video is different to what we see today, I believe this had to do with what the game was about. While the extended version ties into what we have, It gave away a bit too much info from Freelancer that we get from playing through SP. If we had THAT startup video, then we would be on the lookout for Nomads the entire time, up until we actually meet them. Because they removed that part of the video. We don't KNOW about the Nomads until we actually meet them.
EDIT: after reading a previous post about the nomads, I have noticed that the nomads charge their 'cruise engine' right before they cloak. I have also prevented a nomad from cloaking by shooting it with a Cruise Disruptor. So I think its safe to assume that instead of engaging cruise, they engage a cloak.
While being quite funny, your sig was the biggest one i've ever seen so far. No more than 700x250 please. ~utrack http://pastebin.com/SYQXBufs