If you want all or selected Media items to be available for anyone who visits your site then you will need to make your site, or a specific Collection public.
1) If you only have a small number of videos you want to be made public then create a new Collection called "Public" and add all the Media you want to be made public to that Collection.
2) To make a large majority of your videos available to the public, keep the media items in their current Collections and add the public group to several of your Collections.
3) To make your entire site available to public add the public group to your top level Collection (as shown bellow).
Start by logging into your Admin Panel.
Next, click on the Collection you want to make public and click "Manage" in the right sidebar next to "Shared with".
A "Share Collection" box will pop up. Enter the word "Public" into the "Invite existing user and groups" bar, select a role for the public group, and click "Share".