public class VIDEOPERSON{public string VIDEONAME { get ; set ;}}
.
.
public List<VIDEOPERSON> VideoPerson = new List<VIDEOPERSON>();
VideoPerson.Add(new VIDEOPERSON { VIDEONAME = "D:\\aWPFc#\\ProgramByHelpFrmUTube\\WPFControls_2\\WPFControls_1\\Chees00.mp4" });
VideoPerson.Add(new VIDEOPERSON { VIDEONAME = "D:\\aWPFc#\\ProgramByHelpFrmUTube\\WPFControls_2\\WPFControls_1\\Chees01.mp4" });
VideoPerson.Add(new VIDEOPERSON { VIDEONAME = "D:\\aWPFc#\\ProgramByHelpFrmUTube\\WPFControls_2\\WPFControls_1\\Chees02.mp4" });
ComboBox1Mp4.ItemsSource = VideoPerson;
.
.
private void ComboBox2Mp4SelectionChangedClick(object sender, SelectionChangedEventArgs e)
{
int id = ComboBox1Mp4.SelectedIndex;
Uri ww;
ww = new System.Uri(VideoPerson[id].VIDEONAME);
Media1.Source = ww;
}