In order to post YouTube on your wordpress.com blog follow the following instructions:
1. Click on the YouTube window
Clicking on the YouTube window will bring you to YouTube’s website.
There you will find the YouTube URL:
2. Highlight and Copy the URL found
3. Insert the following code:
4. Paste the URL copied in step 2 into the code after the equal sign
5. Save and Publish
Notes: Make sure you do not include spaces in the brackets; doing so will only display the code as text.