When adding a YouTube video through the cut and paste of the url method into the editor of a wiki page (with the YouTube link filter on) the video is displayed more than once.
If you use the Moodle Media button it works fine and only displays one copy.
I think this is because the cut and paste method generates text like (<a href="http://www.youtube.com/watch?v=LO3csMriin8">http://www.youtube.com/watch?v=LO3csMriin8</a>. This has two links in it.
This method does work on normal pages without a problem.