That specific 8500 (core i7 3770) is faster than that specific 8700 (core i5 4440).

I purchased that exact 8500 for a family member two years ago and it is a great system.

That specific 8500 is third generation core i7, so the main difference is four cores plus hyperthreading which will help with video editing.
That specific 8700 is fourth generation core i5. four cores, without hyperthreading, smaller HDD, newer graphics card.

If you are patient and can wait a few weeks and watch for the deals, you can likely find an 8700, with a fourth generation core i7 4790 in the $625 to $650 range. 

http://slickdeals.net/newsearch.php?q=8700&searcharea=deals&searchin=first

Personally, I would hold out for an xps 8700 core i7 system as it is better today and a more solid foundation for the future, but the 8500 with the i7 3770 is not a bad system.

http://www.costco.com/.product.100150672.html?cm_sp=RichRelevance-_-itempageVerticalRight-_-CategorySiloedViewCP&cm_vc=itempageVerticalRight|CategorySiloedViewCP

If you have access to Costco, several 8700s are "on sale". This one will absolutely crush minecraft as-is, and with a future graphics card upgrade can play just about any game.