Pilot DAR, to insert a Youtube link:
Go to the video in question and copy everything after the "=" sign by highlighting it and pressing CTRL and C on your keyboard.
Go to "edit post" now, seeing as you've already posted it and delete what you've already tried.
Click on the "youtube" symbol to insert that in your post. Then put your cursor in the middle of the insert and press "CTRL" and "V" to insert the link to the video.
Make sure you haven't included the "="; you need everything after that.
That should do it!