I'm hugely dubious of Loose Change's conclusions in general - its methodolgy is to pick up on a few 'unexplainables' in the conventional 9/11 narrative and use each one as a springboard into a fanciful plot full of "Take a close look at this lampost" and "But how do you explain this plume of smoke?" But of course if you apply the same rigour the Loose Change filmmakers apply to conventional 9/11 knowledge to their film itself, it just evaporates. There's nothing there. Alternatively, you could just skip the more far-fetched bits and buy some of it: reminds me of the conversation I once had with a David Icke fan. "If you skip the bits about the lizards," she told me, "It makes a lot of sense". Sorry, no. The lizards are out the box I'm afraid, and the fact you still believe anything this guy says speaks volumes about the stuff that you'll swallow because you you "want to believe". You are the 21st Century equivalent of the guy camping outside Area 51, training his binoculars towards the sky.
Incidentally, I'd be very dubious that the makers of this are 'liberals', at least not in the Republican bogeyman sense. One paper quoted several times in the doc is the American Free Press, described on the website as "a populist weekly newspaper that reports what the mainstream media does not". Sounds great, eh? Until you get to the copious references to "Zionists" and "the liberal media", not to mention a link to ""the only no-compromise gun lobby in Washington" and various alien-friendly websites. My guess is politically this is coming more from an anti-government/right-wing libertarian/militia perspective