The Fast Forward button skips seemingly randomly through the files. It's roughly 1 minute per second you hold the button down.
The fast forward could either gradually increase the longer you hold down the button (i.e. 2x at first, 5x after 5 seconds, 10x after 10 seconds for long files).
Or it can be DVD-Style Fast Forward, with each click adjusts the rate, 1 click = 2x, 2 clicks = 4x, 3 clicks = 8x....
The percentage bar should also respond to clicks/drags. This is a very basic feature, you should be able to click on the bar and the player will seek to that position.
