Here are some errors I found today while working them through with a class. I found it strange that I didn't catch it before.
The code referred to at the bottom of the page should be in the demo's Draw method, not the Update method.
Pages 99 - 103:
Code samples are using the playerIndex in the GamePads arrays. The playerIndex member field is not introduced until later on page 106 for the Split Screen demo.
Page 102 - 103:
We should create an overridden Constructor for the FirstPersonCamera class that looks something like this:
public FirstPersonCamera( Game game )
: base( game )
Without the above, the code would not compile and will give an error.
Hope this helps,