ActiveX controls are small programs, sometimes also called "add-ons," that are used on the Internet. They can enhance your browsing experience by allowing animation or they can help with tasks such as installing security updates at Microsoft Update.
Some Web sites require you to install ActiveX controls to see the site or perform certain tasks on it. When you visit such a site, Internet Explorer asks if you want to install the ActiveX control.
Here's an example of an ActiveX message:
The Web site that provides the ActiveX control should tell you what the control is for. It should also provide relevant details on the Web page before or after you see the warning.
What are the risks?
Unfortunately, ActiveX controls are like any other software program-they can be misused. They can stop your computer from functioning correctly, collect your browsing habits and personal information without your knowledge, or can give you content, like pop-up ads that you don't want. Also, "good" ActiveX controls might contain unintended code that allows "bad" Web sites to use them for malicious purposes.
Given these risks, you should only install ActiveX controls if you have information about the Web site that offers the control and the publisher that created the control. With this information you should then decide if you're willing to trust your personal information to the Web site and to the publisher. For more information about how to decide if you trust a Web site, see How to recognize spoofed Web sites.
Here's a good rule to follow: If an ActiveX control is not essential to your computer activity, avoid installing it.
What should I do if I don't want to install an ActiveX Control?
When you choose to install an ActiveX control, Internet Explorer displays a dialog box that identifies the publisher and asks if you want to run the file. Click Don't run if you do not trust the Web site and publisher.
For more information, see How to remove an ActiveX control in Windows.
Information from http://www.microsoft.com/protect/yourself/downloads/activex.mspx
Mac users will need to download Flip4Mac to play WMV videos. The plugin can be downloaded from the link below.