Algodoo

@Mylar -- If you click on the "Help" link right next to the "Add reply" button, it shows the command syntax for displaying a clickable link to a YouTube video in comments and in scene descriptions. There is one important note that the Help page does not explain, and that is the url must begin with "http" (not https). So, after entering the url and other stuff in the command, simply delete the "s" and then it should work as a clickable link.