MediaTimeline and Binding

I'm trying to create a simple Media playlist player using MediaTimeline.
In all of the examples that I saw that Source property is hardcoded.
When I try to set the Source using binding I get "Must specify URI." error.

I'm attaching here a full XAML source that can repro the problem.

<Window x:Class="PureXAMLPlayer.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:sys="clr-namespace:System;assembly=mscorlib"
Title="Window1" Height="517" Width="905">

<Grid>
<Grid.Resources>
<x:ArrayExtension Type="sys:String" x:Key="Data">
<sys:String>C:\Program Files\Microsoft
SDKs\Windows\v6.1\Samples\WPFSamples\GraphicsMM_Media\MediaGallery\csharp\bin\Debug\media\xbox.wmv</sys:String>
<sys:String>C:\Program Files\Microsoft
SDKs\Windows\v6.1\Samples\WPFSamples\GraphicsMM_Media\MediaGallery\csharp\bin\Debug\media\xbox.wmv</sys:String>
<sys:String>C:\Program Files\Microsoft
SDKs\Windows\v6.1\Samples\WPFSamples\GraphicsMM_Media\MediaGallery\csharp\bin\Debug\media\xbox.wmv</sys:String>
<sys:String>C:\Program Files\Microsoft
SDKs\Windows\v6.1\Samples\WPFSamples\GraphicsMM_Media\MediaGallery\csharp\bin\Debug\media\xbox.wmv</sys:String>
<sys:String>C:\Program Files\Microsoft
SDKs\Windows\v6.1\Samples\WPFSamples\GraphicsMM_Media\MediaGallery\csharp\bin\Debug\media\xbox.wmv</sys:String>
<sys:String>C:\Program Files\Microsoft
SDKs\Windows\v6.1\Samples\WPFSamples\GraphicsMM_Media\MediaGallery\csharp\bin\Debug\media\xbox.wmv</sys:String>
</x:ArrayExtension>
</Grid.Resources>

<Grid.ColumnDefinitions>
<ColumnDefinition Width="146*" />
<ColumnDefinition Width="737*" />
</Grid.ColumnDefinitions>

<Grid DataContext="{StaticResource Data}">
<Grid.RowDefinitions>
<RowDefinition />
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>

<ListBox HorizontalAlignment="Left" Width="230" Name="List"
ItemsSource="{Binding}" IsSynchronizedWithCurrentItem="True" />


<StackPanel Grid.Row="1">
<Button>Play
<Button.Triggers>
<EventTrigger RoutedEvent="Button.Click">
<EventTrigger.Actions>
<BeginStoryboard Name="myBegin">
<Storyboard>
<MediaTimeline
Storyboard.TargetName="myMediaElement" >
<MediaTimeline.Source>
<Binding ElementName="List"
Path="SelectedItem.Content"/>
</MediaTimeline.Source>
</MediaTimeline>
</Storyboard>
</BeginStoryboard>
</EventTrigger.Actions>
</EventTrigger>
</Button.Triggers>
</Button>
<Button>Stop</Button>
<Button>Pause</Button>
</StackPanel>
</Grid>

<MediaElement Grid.Column="1" Name="myMediaElement"
HorizontalAlignment="Right" Width="737" />
</Grid>
</Window>