MediaWiki is a free software open source wiki package written in PHP, originally for use on Wikipedia. It is now also used by several other projects of the non-profit Wikimedia Foundation and by many other wikis, including mediawiki.org, the home of MediaWiki.
You can use this moodle repository to allow searching, linking and importing media from these wikis.
note: keep the 'commons url' setting blank if you don't know or are not sure. This is a workaround for sites like wikipedia which have another (shared) url to access resources.