private async void DumpButton_Click(object sender, RoutedEventArgs e)
{
await _captureManager.StopRecordAsync();
var data = new byte[_stream.Length];
await _stream.ReadAsync(data, 0, data.Length);
var storageFolder = ApplicationData.Current.LocalFolder;
var sampleFile = await storageFolder.CreateFileAsync("test.mp4", CreationCollisionOption.ReplaceExisting);
await FileIO.WriteBytesAsync(sampleFile, data);
}