Currently there is not straightforward approach to add an overlay logo. What you can do is to edit the ControlTemplate of RadMediaPlayer and place your logo immediately over the MediaElement. In the attachment you can find a sample object demonstrating that. Scroll to line numer 1800 and you will see where I have placed the logo.
However, your idea is great and if there is enough demand, future versions of RadMediaPlayer will provide this functionality out of the box.
If you have any additional questions, do not hesitate to contact us!
the Telerik team
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