Test your SWF file ad on the most common browsers, especially the browsers that your target audience uses. Some users might not have Flash Player installed or they might have JavaScript disabled. Plan for these circumstances by having a replacement (default) GIF image or other scenarios for these users. For more information on detecting Flash Player, see Set publish options for the Flash SWF file format. Give the user control of the SWF file. Let the user control any audio in the ad. If the advertisement is a borderless SWF file that hovers over a web page, let the user close the advertisement immediately and for the duration of the ad.
For the latest information on Flash Player version penetration for different regions, go to www.adobe.com/go/fp_version_penetration.