If you right click on the image, a menu will appear. In Google Chrome you would want to copy the image URL. In Internet Explorer, you want to view the image properties (at the bottom) and then copy the address (URL) by highlighting it and then click copy. After doing either of these, you then post it by clicking the IMG tab in the Irongarm reply box and then pasting the URL between the brackets.
Either copy the address in the address bar at the top of the screen on youtube or go down and click share this video and then copy that URL and paste it between the youtube brackets in the IGX reply box.
In this case, one of the addresses won't allow you to post the video. None of the URLs given may allow you to post the video. Sometimes it requires a little adjusting of the code from the URL (I won't get into this).