The best way to share a file on social media is using the theater link. To find the theater link, first open the file in MediaLab. Then go to Share > Embed and find the link labeled "Theater page".
The theater page is a public link to view a video, picture or audio. It uses the same layout as the share page so it can be branded with a custom background image (see this page for more info).
When sharing the theater page of a video or audio file on Facebook, Facebook will automatically recognize it and offer an embedded player in your timeline.
If you want to share a video or audio file on your own website, you can also embed the player directly.