Ok, I found an easy way. I went to my YouTube video, clicked on the "Share" button below the video. This provided a blue highlighted address which I then copied into the forum post. The address looks odd in that YouTube is spelled youtu.be (see attachment)
For some reason, copying the url from the browser address bar would not work for me. I am using a Mac, not sure if it matters.
Fyi, clicking the embed button did not yield anything useful.
