>>51078315its a program that doesn't have a regular graphics window, you have to open the command prompt and then you get a black window like you've seen those hackers use.
Here's what you do. Go to the folder of ffmpeg where the .exe is.
Hold the SHIFT key, and right click in the folder somewhere. See "open command window here" ?
Click that. And now type ffmpeg.exe and it should be more apparent that you control it with the command prompt and text commands.
If it seems like too much trouble or nerdy shit, its because it is and a lot of GNU/Linux developers seem to think its acceptable to have command line programs in 2015. Nobody except hackers, geniuses, and people who have to work with computers as their job (me) can get a "CLI" to do useful things usually. Its just too different than how you learned to use a computer. But it is possible and if it interests you, you can usually learn a lot just by typing ffmpeg.exe /help or ffmpeg.exe help
and seeing what comes out.