When comparing nerd dicks, 15 mins sounds impressive but after fiddling with the Xbox One, I couldn't even see myself in situation where I would record 15 straight mins of gameplay. The "Xbox Record That" is perfect. 30 secs is perfect. You get a bad ass sniper kill, a bad ass kill streak, a pick six or monster dunk, that 30 sec covers it as long as you remember to say "Xbox Record That". It's also great for getting little mini clips for a montage of you're into that. Who watches a 15 montage?
I'm completely happy with the way M$ Has implemented this.