Sure. This is one of the best ways to promote your video. Using social media is a great way to reach and grow your audience. Posting on Facebook, Twitter, Tumblr, etc. will create even more ways for people to find you.
Here is a good way to get started:
1. Click on 'Videos'
2. Select the video you want to share
3. Click on 'Promote'
4. Use the sharing buttons to share to different Social Networks like Facebook, Twitter or Google+.
Your audience will be able to purchase the video directly from inside the browser of the facebook or twitter app.