Maybe someone else will read this post having the same problem. Disabling hardware acceleration on flash streaming videos WORKS (it worked for me ). Simply RightClick on video -> settings -> uncheck "Enable Hardware Acceleration".
It must be something with videodrivers. Goodluck!
Yep. The same thing happens to me. And I also have a Gigabyte 560TI, 2500K, 4GB ValueRam. No overclock around. Maybe is something with nvidia's latest drivers. I'll disable hardware acceleration and see what happens.