Stuck between i5-3570k and i7-3930k

Which of the two CPUs is better for my purposes (gaming/hd video editing)?

Obviously the answer might easily turn out to be the i7, especially when used for video editing (hyper-threading, more cores and what not), but recently I've read here and there that the i7 is actually a bit worse at performing during gaming. So where at first I thought the i7 was the same, if not better, at performing in-game, I'm now confused.

I'm almost certain I'm still correct in assuming this i7 model will serve me better than the i5 for video editing, but can someone please help clarify the gaming aspect of it?

Also, can someone help clarify the pros/cons of Sandy E Bridge (this i7 model) and Ivy Bridge (this i5 model)? I read some controversy between the two, architecturally one is better than the other for gaming, I even read something extreme saying that the Ivy performs 5-10% "faster" than the Sandy.

Another question I have about CPUs, how do more cores and hyper-threading exactly help with video editing? I'm certain they do, as I have experienced it myself, (render times are much shorter, much smoother playback during editing etc.), but how is this achieved (the more nitty-gritty detailed the answer, the better).

Thank you so much!

PS: Budget/value/bang for buck is not to be brought up, I am aware the i5-3570k is among the best valued Intels for high-end Gaming builds. This is purely hypothetical and performance based discussion!