Where can I find the "Animate Physics" option (tick box) within the Animator component in Inspector?

I have a model called “Girl” with Animator component:
31632-dfwf.png

However, it seems to be missing an option called “Animate Physics” which is demonstrated in this Unity Tutorial: Unity 4.0 - Mecanim Animation Tutorial - YouTube (at 5:39) , and here is the screenshot of it:
31633-untitled23.png

I’m currently using Unity version 4.5.3f.3, and I’m wondering, could the missing option be caused by simply that the updated version has removed this option from the inspector, or have I got some Unity setting incorrectly?

You will have to change the value in the “Update Mode” select box. Instead of “normal”, choose “Animate Physics”.