You won't be able to do that using an Arduino microcontroller. You need far more memory and processing speed than a microcontroller can provide. You might be able to do it using one of the recent hybrid Arduinos which have a small PC embedded but a compact computer such as RPi or BeagleBone Black would seem like a more sensible approach. Even so, you will probably end up needing to create your own video adapters to connect between the input and output devices. This strikes me as an extremely advanced project.