forgot to put on load functionality .code goes here
xaml
<mediaelement height="Auto" horizontalalignment="Stretch" margin="-12,-45,0,0" name="mediaElement1">
VerticalAlignment="Stretch" Width="Auto" Loaded="mediaelement1_loaded /></mediaelement>
.cs
private void mediaElement1_Loaded(object sender, RoutedEventArgs e)
{
//functionality
}