The 8150 is better for encoding in most cases but its not worth the price considering youll only get a little extra performance. For Encoding you would be best saving for an Ivy bridge i7.
RAM is everything when it comes to video editing, definitely throw in another 8gb, no more though on that processor.
I would just stick with the one youve got at the moment, It works well for editing and encoding. Make sure youve got Multi core rendering enabled in the settings of the program you are using too.