Is bin Ladin video fake?
Since I do not have the expertise that these people whom I am going to direct you to have, I think it best to do this in that manner.
Here are some of the sources:
Laura Mansfield web site: Bin Laden stresses martyrdom in short segment of new As Sahab video.I would personally go to Laura Mansfield's and Counter Terrorism Blog for any serious discussion of what is happening in the world today. They are very prolific in history as well.
Video Web Link from Laura Mansfield web site.
CNN: Newly released bin Laden video calls for martyrdom.
ABC News: Possible New Message From Osama Bin Laden.
FOX News: Osama Bin Laden Appears in New Video, Officials Probe Authenticity.
Hadeeth Sunnah Sahih Bukhari, Book 52. Fighting for the Cause of Allah (Jihaad). Quote from Volume 4, Book 52, Number 54.