If you think you may have received a suspicious video link, hover your cursor over the link to see where it's redirecting you (look in the lower left corner of your browser's status bar). If the link doesn't direct you to youtube.com, it's not from us. Some people have recently been creating emails to appear as if they were sent from YouTube.
If you've already clicked a suspicious link, you may want to scan your computer with anti-virus and anti-spyware software to discover any malicious software that may have been installed on your computer without your knowledge.
For more information on this issue, go here: http://www.avertlabs.com