<Window x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="275" Width="491" >
    <Canvas Height="240" Name="canvas1" Width="444">
        <MediaElement x:Name="Video" Canvas.Left="72" Canvas.Top="12" Height="158"  Width="301" Source="D:\EXP\MyVideo8\WpfApplication8\bin\Debug\Become happier.avi" LoadedBehavior="Manual" UnloadedBehavior="Manual" />
        <Button x:Name="Play"  Content="Play" Canvas.Left="112" Canvas.Top="180" Height="23" Width="74" Click="Play_Click" />
        <Button x:Name="Pause"  Content="Pause" Canvas.Left="192" Canvas.Top="180" Height="23" Width="74" Click="Pause_Click" />
        <Button x:Name="Stop" Content="Stop" Canvas.Left="272" Canvas.Top="180" Height="23" Width="74" Click="Stop_Click" />
        <Slider x:Name="TimerSlider" Canvas.Left="26" Canvas.Top="209" Height="27" Width="398"/>
    </Canvas>
</Window>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Windows.Media.Animation;
using System.Windows.Threading;

namespace WpfApplication1
{
    /// <summary>
    /// Логика взаимодействия для MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {

        public MainWindow()
        {
            InitializeComponent();
        }

        private void Play_Click(object sender, RoutedEventArgs e)
        {
            Video.Play();
        }

        private void Pause_Click(object sender, RoutedEventArgs e)
        {
            Video.Pause();
        }

        private void Stop_Click(object sender, RoutedEventArgs e)
        {
            Video.Stop();
        }
        
    }
}