This three-part video is pretty comprehensive.
"September 11 - The New Pearl Harbor" - Full version
http://www.youtube.com/watch?v=O1GCeuSr3Mk
http://www.youtube.com/watch?v=K7mDXHn_byA
http://www.youtube.com/watch?v=DegLpgJmFL8
It has the latest analyses. I even recommend it to people who've seen the earlier videos.
This video explains the motives.
http://topdocumentaryfilms.com/new-american-century/
It's not always easy to get people to look at the proof that the government did it. We can get people's attention with something really clear that doesn't take long to look at such as this.
http://0911.voila.net/index4.htm
(fifth picture from top)
That might make them think a long video is worth watching.