I just got the i5-3570K, and it's slick.
I OC'ed it up to 4.3 GHz with no issues, and it's still as cool as a panda.
The iGPU came in handy because my graphics cards still have not arrived so I'm using the integrated graphics to run a 1920x1200 display and the processor wouldn't have batted an eyelid if it had one.
I render videos too, but since my graphics cards aren't here yet, I haven't given it a try. The thing is HyperThreading is that the added cores are not physical cores and therefore, you only get about 20 maybe 30 percent of performance increase.
Let's assume you give each render thread 2GB of RAM (which is minimal for HD video). Assuming 8 threads, that's already 16GB of RAM, which leaves nothing for the compiler process itself. So unless you want to drop coin on at least 32 GB of RAM in order to allow you to give 3GB of RAM to each render thread, don't worry about HyperThreading and save some money by getting the i5-3570K.