Developer / Publisher
Details and Conditions
From Valve's Video Policy:
"Use of our content in videos must be non-commercial. By that we mean you can't charge users to view or access your videos. You also can't sell or license your videos to others for a payment of any kind."
"You are free to monetize your videos via the YouTube partner program and similar programs on other video sharing sites."
See more details by clicking the "source" link below.