Dim MyMprList As New List(Of String)
 
For i As Integer = LB_DXF.SelectedItems.Count - 1 To 0 Step -1
    '....
    '....
    MyMprList.Add(MprName)
Next i

Dim MprLocalFile As String = "C:\maschine\mp4\"
 
For j As Integer = 0 To MyMprList.Count - 1
    Process.Start(MprLocalFile & MyMprList.Item(j))
Next

mfg.

Dirk