Millions of people stream Netflix content on their computers, but few wonder how it works. Netflix runs in computer Web browsers with the help of a plugin called Microsoft Silverlight — and Silverlight has coding errors that can be exploited to bypass its security measures. A new cybercrime campaign is using fake advertisements as a launching point, hitting Silverlights vulnerabilities to install malicious software on computers, according to San Jose, California-based networking giant Cisco, which discovered the attacks.