I just installed Facebook video chat after finding the directions over on Engadget.
STEP 1
Go to the Facebook Video Calling Getting Started Page.
Image: Facebook Video Calling - Get Started
STEP 2
Click GET STARTED.
Image: To set up video calling on Facebook
STEP 3
Click SAVE when prompted to save the Video Calling Plug-in.
The video calling plug-in is downloaded.
Step 4
You then open the downloaded file to install it.
This takes a few moments.
RUN the saved file.
Image: Facebook Video Calling - Install Progress Indicator
Once installed, the CALL button with an image of a video camera shows up on friends pages who have installed the Video Calling App.
Once installed, there will be less of a barrier for Facebook users to make video calls.
It'll be interesting to see the adoption.
Update:
The Facebook Blog: Call Your Friends Right From Facebook
CIO: Facebook Video Calling: How to Get Started and Adjust Privacy Settings
Update II:
When on a call, if you have multiple cameras attached to your computer, you can switch between cameras using the camera dropdown menu at the bottom of the video chat window.