That's tough one, but thanks for pointing out the need for such functionality. In Sitefinity 4.x you're able to upload/play *.wmv videos using the Videos library and the built-in Video and Video Gallery widgets. You can also upload/play flash content (*.swf format only) through the Content Block text editor (go to Edit content -> More formatting options -> Flash Manager (you'll notice the little flash video icon among the tools in the toolbar)). Tou use this functionality, you'll need to create a folder "Files" in the root of your SitefinityWebApp and upload your flash videos there either through Adminstration->FIles (max file upload size is 200KB) or using Windows Explorer.
One last note - you can visit the Sitefinity Marketplace
where a module for our 3.7 version is offered, which supports playing *.flv video format.
I hope you find the above information useful. If you have any additional questions, please do not hesitate to write back
the Telerik team
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