The short answer is anyone who has the permission to create a public page in their role can enable one of their own videos for external viewing via the public page. This will require:

• Enabling the public page feature for the media portal. This is a global setting managed by the administrator.
• Assigning the EnablePublicPage permission to the user’s role.

Even with the permission a user can only enable their own videos for public page access. Furthermore, only videos that are available to all portal users (i.e. privacy setting is set to Public) can be enabled for a public page.