<Canvas xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
  <MediaElement Source="C:\Users\Public\Videos\Sample Videos\butterfly.wmv"
  Opacity="0.5">
    <MediaElement.Clip>
      <EllipseGeometry Center="220,220" RadiusX="220" RadiusY="220"/>
    </MediaElement.Clip>
    <MediaElement.LayoutTransform>
      <RotateTransform Angle="180"/>
    </MediaElement.LayoutTransform>
  </MediaElement>
  <MediaElement Source="C:\Users\Public\Videos\Sample Videos\butterfly.wmv"
  Opacity="0.5">
    <MediaElement.Clip>
      <EllipseGeometry Center="220,220" RadiusX="220" RadiusY="220"/>
    </MediaElement.Clip>
  </MediaElement>
</Canvas>