Solved it!
In the last methode: Copyall:
foreach (FileInfo fi in source.GetFiles(“*.MP4”))
{
fi.CopyTo(Path.Combine(target.ToString(), fi.Name), true);
total += (int)fi.Length;
copied += (int)fi.Length;
copied /= 1024;
progressBar1.Step = copied;
progressBar1.PerformStep();
label1.Text = (total / 1048576).ToString() + "MB van de " + (maxbytes / 1024).ToString() + "MB gekopieƫrd";
label1.Refresh();
}
solved File copy only x file extension