RadMediaPlayer renders HTML5 video tag on modern browsers and supports the same formats supported by the standard video tag:
Since 2014 Q1 release version of Telerik Web UI controls, for older browsers which don't support HTML5 natively, Internet Explorer 8 and 7 in particular, the player provides a Flash fallback method to play the video or audio file by rendering a Flash object.
And since the player now supports rendering Flash player object, playing flv
videos is achievable and it will be supported with the upcoming releases.
I hope the clarification was helpful.