With the upgrade all you have to do is leave the link to the youtube page the video is on. If your link does not convert to a video it's usually because youtube put to many characters on the end of the link. Example:
The link above has to many characters on the end. 99% of the time you have to delete the extra stuff all the way back to the "&" sign. Which by the way includes deleting the "&" sign as well. Which means the link above should look like this:
Instead of the big long link. Once the extra stuff is deleted you video will appear as below.
No more bbcode required. Just post youtube page link minus all the extra garbage on the end if it exists (does not exist on every link) and the forum program will post it as a video.