Aral and Ian video links

Added the video links to Youtube because we have the permission from Aral and Ian.

The videos are still set to "Nicht gelistet" so it is only accessible via the link.
After the pull request is merged and the Tweet and FB post is sent out, I'll change the settings of the videos to "Öffentlich" and inform Aral and Ian via mail.

I'd say let's release two videos at a time because waiting until all are approved could take a while.