This may not have been the best idea, but I found the video of Nicholas Berg on ogrish.com and watched it. I suggest you think carefully before watching it yourself, it is more disturbing than you might think.
The difference between the actual video and the limited images in today's papers is astonishing. The newspapers pictures look calm, quiet. The video is swift and horribly brutal. The most disturbing thing is hearing the murderers shout "Allahu Akbar" over and over again.
I watched it because I think it's important to view the truth of things. I hate modesty censorship of news. But there are some things you may prefer not to see.
Update: this BBC article is about the news media's attempts to explain the video without actually showing it.