The tricky bit is to also be able to play a still (Tif, JPeg .....) after a video for either a fixed time or be triggered manually to then play the next video in the playlist which will then go to a still again and so on.
I think you'll be best off creating a motion JPEG or short video clip with the stills.
And have a keypress to go to black if required.
That seems like a bit much to ask of a video player. Why would anyone ever need that?
My favourite video player is ALShow (used on my 3rd monitor mostly). It has a similar function for that (press ESC), but it minimizes itself to the taskbar notification area (system tray).
I think you need to rethink how the presentation will work. Most likely you will need human interaction there, especially for the stills.