While posting a link, does it work with the shortening, or do I need to post the whole link in order for Twitter and YouTube to actually embed the video in the post??

There are two ways. You can either:

• Post a YouTube link.
• Or, alternatively (and better), just upload the video you want to publish to the Digital Library, and then publish it to the Twitter network. In Post Manager just click the Library icon, then the Videos tab and select the video you want to publish.