1. Replace the default youtube bbcode with this one.
2. Go to System Admin tab.
3. Click the BB Codes icon.
4. Find "Colorbox YouTube Flash Video Embedder" in the list.
5. Click Enable.
How to use:
After you followed the "Installation instructions" go to any option that is using bbcodes and click the YouTube icon and you will get this tag: [ youtube ] [ /youtube ]
Inside the tag add the YouTube ID, you will find it at the end of a YouTube video, Ex: youtube.com/watch?v=ID
The difference from this version and the one from the pack is that this one won't let you use full links, you will need to use just the ID.