1. Locate the video you want to post on the YouTube site. Open its page.

2. Locate the box on the upper right of the page with two text fields named URL and Embed.

3. Click on the text in the Embed text box. Select all of it and copy it.

4. On your Drupal site, choose Create content and pick the content type where you want to post this video.
I choose Blog.

5. Paste the code you copied from the YouTube embed text box into the Body box on your Drupal Create content form.

6. Click on the Input format section to open it.

7. Click on the Full HTML radio button.
This is what allows the code you pasted in the Body field to be interpreted correctly by the Drupal software. If you don't do this, Drupal will simply ignore the code and your video won't show up.

8. Click Save.
Your video will now be published.