How to Link URLs Within a YouTube Description
By Marina Martin
A YouTube video's description appears beneath the video each time someone watches it. Many video creators use this descriptive space to convince potential viewers to watch the clip and to promote the creator's cause or other work. While YouTube doesn't allow HTML tags in descriptions, you can insert a URL to another website in the description. YouTube will automatically convert that URL into a clickable link.
Log in to your YouTube account.
Click your username in the top right corner and select "My Videos."
Click the "Edit" button next to the video you want to edit.
Type the URL you want in the "Description" box. Include the "http://" at the beginning. For example, you would type: "http://www.google.com".
Click "Save Changes" at the bottom of the screen. Your video's description now has a clickable link to the URL you inserted.