@Liz - converted no problem
The [media] tags (or any tag that has the full URL in it) is simple. The code setting is
media and the conversion is
\1
I ran it on your test board and it converted all the media tags to url tags.
You can then use the rebuild posts tool to convert those to your new codes.
The GARS thread was fine. The problem was that either the posts need rebuilding OR you need to edit/resave for AME to convert the URL tags.
Looks like your [youtube] code will also be straight forward to convert. Do it the same as the media explained above.
Just make sure you read the admicp help on the converting tool and rember that the tool only converts tags back to normal URL tags. After that, use rebuild posts tool to convert them to AME tags.
HTHs