youtube extensions won't work in Mediawiki

Hi. I put YoutTubeTag.php & youtubep.php and youtube.php into /extensions and placed

include("extensions/youtubep.php");
include('extensions/youtube.php');
require_once('extensions/YouTubeTag.php');

at the bottom of my LocalSettings.php.

I placed the following in to the wiki page:

<youtubep>1K7h_pj569s</youtubep>

<youtubevideo>1K7h_pj569s</youtubevideo>

<youtube>1K7h_pj569s</youtube>

<youtubevideo>pJElsNaC6yQ</youtubevideo>

<youtube v="pJElsNaC6yQ" />

And none of the strings work. Any ideas what could be wrong. Thanks in advance. Bruce

I didn't change the LocalSettings.php in the home directory, so that was my first error. But now when I do I get:

Warning: require_once(/extensions/YouTubeTag.php) [function.require-once]: failed to open stream: No such file or directory in /home/.puree/zentek/dharmaflix.com/w/LocalSettings.php on line 126

Fatal error: require_once() [function.require]: Failed opening required '/extensions/YouTubeTag.php' (include_path='/home/.puree/zentek/dharmaflix.com/w:/home/.puree/zentek/dharmaflix.com/w/includes:/home/.puree/zentek/dharmaflix.com/w/languages:.:/usr/local/php5/lib/php') in /home/.puree/zentek/dharmaflix.com/w/LocalSettings.php on line 126

How do I fix that. The path must be wrong, but it is what the Mediawiki instructions suggest it should be. Still learning. Sorry for the newbie questions. Bruce