There was a problem with wiki pages in the HTML markup syntax. If they
contain a link and the link text has a URL in it, that URL was converted
into another link. But it was not correctly nested and it caused
additional troubles with filters (particularly the multimedia filter if
the URL was a video such as on youtube).
The solution here is similar to what we do in filters. We protect the
whole explicit link so that its content is not further parsed. That
prevents the inner URL to be converted into another link and the
explicit link has the full control.
David Mudrák