The MSN Video folks have updated Soapbox on MSN Video to allow users the ability to subscribe and add someone's video “stream” to Zune. You'll notice a new Zune icon next to the RSS icon on people's profiles on Soapbox for MSN Video.
When you click the Zune icon, it adds the video feed to the Zune software. For example - when you go to my profile on Soapbox for MSN Video (where I host my videos I post here) and click the Zune icon - my video feed will appear in the Zune software.
Any new videos I publish to Soapbox on MSN Video will then be downloaded into the Zune software which can also be synced to a Zune device. When I post video demos of cool Windows or Windows Live features and announcements - you can put them on your Zune and show your friends.