Originally Posted by
site1Q84 You take the last part of that YouTube link -- the "y1_HPx6h1do" part -- and put it with the words YT and /YT both in brackets around the start and finish of that "y1_HPx6h1do". So like this, only with [ and ] instead of ( and ):
(YT)y1_HPx6h1do(/YT)
There's a button on the reply box that will do it too. It's the second to last button on the row that has the bold and italics options, etc.
For example, here is one of my favorite Arrested Development compilation videos: