We don't have anything here well produced other than static documentation (user and quick start guides). Wikimedia produced some videos which may be of interest (they are old, but the concepts should be correct). If you have a specific question, we'd be happy to help.

https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=wikimedia+phabricator&tbm=vid

https://secure.phabricator.com/book/phabricator/