The easiest and fastest way to change the look and feel of a control is to edit its ControlTemplate using Microsoft Expression Blend
1. Create a Silverlight application and add a RadMediaPlayer on the MainPage.
2. Right-click on MainPage.xaml and choose "Open in Expression Blend..."
(this option is available only
after installing Microsoft Expression Blend).
3. Once Microsoft Expression Blend opens, you should see something like the screenshot bellow.
4. Right-click on RadMediaPlayer in the "Objects and Timeline"
pane and select "Edit Template > Edit a Copy"
5. This will dump all the resources necessary for editing the look and feel of RadMediaPlayer. From then on it is up to you to decide how RadMediaPlayer will look and behave.
I am attaching my sample project. Give it a try and let me know if you encounter any problems. Also, you can have a look at this list of Silverlight and Blend tutorials
for further reference.
the Telerik team