For anyone who needs to know, or likes a reminder close by (like me)....to embed a video to a discussion:
Go to youtube, and pick your video you want to use, then on the right side, you'll see a text box with the word "Embed" to the left of it. Single-click the cursor in that box once (for some reason on my computer I have to click it twice for it to highlight in blue) and it will select the entire contents. Then right-click in the box, select "copy," then paste it into your discussion.
There are 2 boxes, the top one says URL code, "Embed" is below that.