private async void button_Click(object sender, RoutedEventArgs e)
 {
     StorageFolder videoLib = Windows.Storage.KnownFolders.VideosLibrary;
     StorageFile video = await videoLib.GetFileAsync(@"" + previewPath);
     var upload = new VideoFile { Title = previewPath };
     await InsertVideoItem(upload);
 }
        private async Task InsertVideoItem(VideoFile todoItem)
        {
            // This code inserts a new TodoItem into the database. When the operation completes
            // and Mobile App backend has assigned an Id, the item is added to the CollectionView.
            await videoTable.InsertAsync(todoItem);
            items.Add(todoItem);

            //await SyncAsync(); // offline sync
        }