I recently put this XAML together -- it shows animating a MediaElement with a ScaleTransform, kind of a cool effect watching the video expand from a tiny circle to full size.

<Grid
    xmlns="http://schemas.microsoft.com/winfx/avalon/2005"
    xmlns:x="http://schemas.microsoft.com/winfx/xaml/2005"
 Background="Black"
    >
 <Grid.Storyboards>
  <ParallelTimeline >
   <SetterTimeline TargetName="myVideo" FillBehavior="HoldEnd"
    Path="(MediaElement.RenderTransform).(ScaleTransform.ScaleX)"
    >
    <DoubleAnimation From=".1" To="1" Duration="0:0:3" FillBehavior="HoldEnd"
    AutoReverse="False" BeginTime="0:0:3"/>
   </SetterTimeline>
   <SetterTimeline TargetName="myVideo" FillBehavior="HoldEnd"
    Path="(MediaElement.RenderTransform).(ScaleTransform.ScaleY)"  >
    <DoubleAnimation From=".1" To="1" Duration="0:0:3" BeginTime="0:0:3"  FillBehavior="HoldEnd" 
    AutoReverse="False"/>
   </SetterTimeline>
  </ParallelTimeline>
 </Grid.Storyboards>
  <MediaElement Name="myVideo" Source="C:\WINDOWS\system32\oobe\images\intro.wmv"
        Width="450" Height="400" >
   <MediaElement.Clip>
    <EllipseGeometry Center="300, 150" RadiusX="150" RadiusY="150" />
   </MediaElement.Clip>
   <MediaElement.RenderTransform>
    <ScaleTransform Center="250,200" ScaleX=".1" ScaleY=".1"/>
   </MediaElement.RenderTransform>
  </MediaElement>
</Grid>