windowedMyApp/WindowedMyApp/GifPAge.xaml

<Page x:Class="WindowedMyApp.GifPage"
      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
      xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
      xmlns:gif="http://wpfanimatedgif.codeplex.com"
      xmlns:local="clr-namespace:WindowedMyApp"
      mc:Ignorable="d" 
      d:DesignHeight="450" d:DesignWidth="800"
      Title="DiagramPage">

    <Grid>
        <Image gif:ImageBehavior.RepeatBehavior="3x"
               gif:ImageBehavior.AnimatedSource="Media/animated.gif"/>        
    </Grid>
</Page>