A very short answer: as GDI and DirectX (used to show video) don't live well together, this can be considered to be a too difficult problem to bother. You would need to use DirectX
overlay with
System.Windows.Forms
. See, for example:
http://www.unknowncheats.me/forum/c/62019-c-non-hooked-external-directx-overlay.html[
^],
http://gregs-blog.com/2008/02/26/managed-directx-c-graphics-tutorial-1-getting-started/[
^].
What to do? My advice is:
don't get there, instead,
switch to WPF, which is itself based on DirectX.
Everything in WPF can be made semi-transparent, everything can be overlaid over everything, including video, without any special effort. I tested it; it's very easy.
—SA