Social Share is a free Office add-in which enables PowerPoint to directly share presentations via Facebook and Twitter.
Installing the extension gets you a new tab on the ribbon with various sharing options.
A Facebook button can share the current presentation as a video, or a photo album, or just post a selected area of the current screen.
A Twitter option allows you to select a freehand rectangle on the screen, before uploading it to your account.
Social Share can automatically upload the presentation to OneDrive, and include a link to your post, making it easier to share the content with others.
And if you want to know what everyone else thinks of your work, a View button displays your current Facebook and Twitter feeds in a sidebar.