Video editing really benefits from quad cores and hyper threading. I appreciate you are only looking at "light" editing but my experience tells me not to trust that assessment! Even supposedly light editing uses a lot of performance. You might not be rendering a 4k cartoon with radiosity lighting but you are still processing GB's of files and using heavy algorithms that multi thread well.
AMD is competitive price wise at the low and mid end but the i3's have hyperthreading, which will benefit image and video encoding quite a bit. This often swings it in favour of the Intel's if you can find a decent price platform. But stretching to a quad core on either will benefit your usage pattern greatly.