Just watching this now and love him or hate him it just shows how hard it is to cover Kurt's vocal parts. I remember watching the Nevermind episode of classic albums on the BBC and Butch Vig played the raw vocals and he explained that the tone of his voice led people to think Kurt couldn't sing in tune because his voice broke up in the way usually found in out of tune singers, like myself, (He explained it better!). When you expected it to go out of tune it didn't, then he'd go up a few gears and it was more gruff and raucous but still in tune.
Always nice to see Pat and Krist enjoying themselves though.