this is VJ stuff I think.
which requires seperate programs with seperate hardware controllers...
but thats also for big shows and stuff.
I mean, you want to have video playing on a big screen somewhere from a computer. That means you need a program to output the video in fullscreen and allow you to press different keys that cause different actions, like a fade, to occur to the video as it is playing.
but you can only project what your screen in front of you shows.
if you want to see something like a controller program in front of you that controls different things, you need hardware outputs...
this might be kind of complicated...