This feature is accessible through the "Insert Media" dialog when posting a message. It adds two options (unchecked by default) that allows the user to look for embeddable URLs if the one they submit does not match any active media site. For example, if a user tries to submit a t.co (Twitter's URL shortener) link to a YouTube video
it will not be recognized by default, but if the user checks "Use the canonical URL" then it will be recognized as a YouTube URL.
You can enable or disable this feature in your admin panel. When you install the add-on for the first time or you upgrade to this version, the status of this feature will match your preference for unfurling. If you have unfurling enabled, then this feature will be enabled. Otherwise, it will be disabled and you will have to manually enable it in the add-on's options.
This feature will evolve based on organic usage and your feedback.