Games, AND NOTHING ELSE (excuse all-caps) come close to actually, technically
requiring discrete cards as far as I know.
For best graphics performance without discrete cards though, just get a
Broadwell (not skylake, not Haswell), or ix-5xxxC processor and then go
without a discrete card.
And if I recall correctly video-editing is more CPU intensice than graphics
intensive - maybe a Haswell i7 would serve you better than a Broadwell i5
despite the latter's better graphics.
Long story short, you don't need a gaming card to do video editing. If I were
you and didn't care about free software and didn't want to game but wanted to
do video editing, I'd honestly consider by-passing a discrete card (and if
needed, but probably not, get a Broadwell ix-5xxxC card). It simply isn't
needed.
And rendering .avi and .mp4 don't depend on graphic cards.
