Mike is frustrated because one of the government real estate websites he visits requires Microsoft Silverlight, and they don't support it anymore. Leo says that everyone has moved away from Flash-like players that require a plug-in in favor of HTML 5. But it's not unusual that government hasn't caught up to the new thinking. Leo thinks government should never require proprietary plugins.
Fortunately, Mike can still download Silverlight from Microsoft at microsoft.com/getsilverlight. It not work with Windows 10, however. No modern browsers support it anymore, either. Mike would have to go to oldversion.com and download a previous version of Explorer, but that also has its own security issues.