Can I sue if a video of me was posted online without my permission?

Since you were at work in public view [or at least view of your co-employees], you had no expectation of privacy so you could be videotaped. You might be able to successfully claim that the video was posted to injury you, especially if the commentary accompanying it is derogatory. But you would have to show that people who know you saw the video and developed a negative attitude toward you, unless you can prove actual malice, which normally is difficult to prove. Make a written demand, explaining why in a calm statement, of the person who posted it and the web site that hosts it.