When uploading a video or when editing one from the list of existing videos, use the Click Here if this video is for sale checkbox present at the button of this page to do this.
Once you enable this, you will need to enter the CCBill form settings which is setup with the price you have decided for this video.
IMP: Please note that you will need to set up different CCBill forms with different prices and enter the details of the right CCBill form which has the correct price.
