This is how I do it but that doesn't mean it's the correct way.

I a nut shell copy & paste the code from u tube into your post.

When you select your video in you tube and it is displayed on your screen......
on the righthand side about 3" from top is the word "embed" with a box containing code underneath
copy and paste that code into your post.

That should do it but preview your post to be sure.

I don't remember how to link to the video.

Good luck