Stop Drupal from encoding '&' as '&amp;' in YouTube URLs I embedded a YouTube video inside a "News" node. The input format in use is Full HTML.

When node is saved, the ampersand symbol in &amp;wmode=Opaque is substituted for &amp;amp;wmode=Opaque.

Is it possible to prevent the ampersand in the URLs of embedded YouTube videos is encoded as HTML entity?
Try disabling the HTML corrector on the text format. Also, though, I don't think URL-encoding amphersands in URLs actually breaks them. &amp; should work as a query string parameter separator as well. If not, though, see my suggestion :)