You could encode as many movies at once if you wanted...but considering just encoding 1 takes 100% cpu, when encoding 2, each would have a 50/50 CPU split, hence twice as slow. If you do three, it'd be a 33/33/33 split, hence 3 times slower. Seeing how your english is so terrible, I'll just assume your math is just as bad. If there were 4 it'd be a 25/25/25/25 split, hence 4 times slower. This is considering the priorities on each of these processes are the same and one of them is not taking 99% of the CPU while the other is taking only 1%.