Well done to them if it was without the buff, I'm sure the margin of error is tiny even with full 264 heroic 10man gear. (Technically you can get sanctified (264) t10 via 10man, guessing that was used too.
However if it was with the buff, then in my opinion at least, it means very little if anything at all, considering the 25 man version of it was done without the buff.