@flowrider if your Mac is suddenly lost, or destroyed, now, and if the only immediately available acceptable replacement Mac runs El Capitan: you'll upgrade on day one.
I'm on a Skylake rMB and so far 4k 30FPS and 1080p60 both run flawlessly, no choppiness windowed or fullscreen.
I have a question, how do you feel about creating a browser extension for Safari so Youtube always plays in the highest available format?
Boy, thanks for clearing that up. You made up good hypothetical, why?
one-port USB-C retina MacBook Pro
As I typically do, I will upgrade my casual use Macbook Air right away, and I will hold off on upgrading my Mac Mini until the .1 or .2 release.
Wow, you bought the one-port USB-C retina MacBook Pro? Lucky. I wish I had one too. Apart from the single port issue, it's such a beast of a machine. And its modern GPU has hardware decoding of all common video sizes and framerates.I am extremely jealous. (And to answer your question, it would unfortunately be way too much work to make YouTube auto-select the highest quality. Their player does a bunch of tests to automatically pick a reasonable quality based on bandwidth, screensize, player size, browser capabilities etc.)