OpenGraph Description

Where does the plugin pull og:description information from? I use the All-In-One SEO Pack and have filled in the description in that metabox. Before activating OpenGraph functionality, Facebook would pick up that text as the og:description (inferred).

With the plugin activated, it appears to grab the first words of the post.

Is there a way to have it pull from the description provided by the SEO pack (or even not attempt to designate a description, allowing it to infer as before)?

Otherwise, what standard WP field would be best to use? Excerpt (assuming it in use elsewhere in my theme)?