Promote videos on our site using twitter cards



We are interested in using twitter cards to promote our various products and in particular our four demo videos. As the videos are on one page of our site, can someone provide instructions or tell us if it is possible to promote one particular video at a time. Here is the page the video is on and it is the Template 3 video that we would like displayed inline on the tweets. Also could someone confirm if the service is free as I read the Product Cards was not paid for but we cannot find a link to create a card for the video?

Thanks in advance.