She probably saw "Loose Change", an incredibly inept example of quote-mining and cherry-picking. You can see it on Google Video, if you must.
Here's a humorous response:
http://www.thebestpageintheuniverse.net/c.cgi?u=911_morons
and another funny site mocking Loose Change
http://loosetrains911.blogspot.com/
and here are some more serious sites that debunk the conspiracy nuts
http://www.911myths.com/index.html
http://www.debunking911.com/index.html
http://911conspiracysmasher.blogspot.com/
http://screwloosechange.blogspot.com/
Perhaps the most damning words against these guys comes from their own statements.
Watch "9/11 Deniers Speak" on youtube
http://www.youtube.com/watch?v=6uFNBpjZCI4
This is a video that debunks the Loose Change video. It's excellent and rather than waste your time watching the Loose Change video you should just watch this one because it follows the video along and pauses to debunk each point the video makes. It's a little long, but excellent viewing.
Click on Videos in the left hand corner to watch the 3 part video
http://www.lolloosechange.co.nr/
Thank you for this - forwarded to my liberal ex-girlfriend. I think she was a little skeptical of the 911 conspiracy theory - she was one of those rare libs with an iota of common sense - but hopefully this should help her understand the science.
I finally had a chance to look at the Loose Change video and must admit that I am really beyond appalled. I'm pissed, I'm angry. These people are making things up to try to be relevent.