To post a YouTube video on Facebook, you can follow these steps:

1. Go to YouTube.com in your browser and search for the video you’d like to share.
2. Click on the video to open it.
3. Click the Share button below the video.
4. Then click the Facebook icon that appears below.
5. A new window will open.
6. In the text box, add a caption to your post if you wish.
7. Then, click Post to Facebook.

You can also copy the link of the YouTube video and paste it into your Facebook post. Your viewers can click on the video thumbnail and be directed to the YouTube website.