That guy also posted some pretty specific requirements which were needed to pull it off, like Ziggs and Master Yi getting the double kill bot pre 3 minutes. And the guy freely admitted that, "Now I'm not saying there's nothing me or my team could have done to stop it... heck, we won that game anyway."
Judging that minions dont reach the lane until around 2 minutes, that is not "normal conditions". Thats basically PvE in an empty lane. No botlane should get double-killed pre-3 minutes if they have their summoners up. Its not a normal condition - its highly abnormal. Its not impossible, but abnormal.