I meant.... When you click your links, the video then appears.

However, others have been using the GUI. Using the "video" link on the GUI..... a box appears so you can paste the youtube video URL (which you've copied from youtube or wherever) in to it.

Then you click "preview" and when it's working OK you can choose the size and position of your video.

When posted (and after you've clicked "post"), a still of the video appears along with the arrow to click to play the video.

(I posted all that so that those that have never tried it will know what I'm on about).