You can use YouTube to send private messages and comments to other YouTube users:
- Start by clicking the username next to one of the user's videos. This will take you to the user's Channel page.
- Once you're on the user's Channel page, click the 'Send Message' link underneath their thumbnail.
- You can then write a message just like an email.
- When you're done, click the 'Send Message' button.
The user will be able to view your message in their YouTube Inbox. They'll also receive an email letting them know they've got a new message to read.
