If you are embedding videos on your own website, it is possible for others to copy the embed code from your page's source code and then embed the video on his or her own site. You may want the video to remain embedded only on your site. Allowed Domians limits where your embedded videos can play, even if someone takes the embed code from your page.
To use Allowed Domains, first click on the 'Account' link in the upper right hand of the website. Then click on the 'Video Settings' tab. Then, simply add in a list of domains or subdomains separated by commas for your site. Wildcard (asterisks) are accepted for subdomains. An example list might be:
site1.com, www.site1.com,*.site2.com, videos.site3.com
This list will allow your embedded videos to play on site1.com and www.site1.com (but not on any subdomains on site1.com), on any subdomain on site2.com (but not on site2.com) and only on site3.com under the "videos" subdomain.
Please note: If you would like your video to play on example.com and www.example.com you must add both to this setting or use a wildcard. Ex:
example.com,www.example.com
or
example.com,*.example.com
In order to allow playback on Facebook while using the Allowed Domains feature, you'll need to add the following to your list of allowed domains:
s-static.ak.facebook.com