It looked like a secret red portal within act 5 he went to

I just found out that this secret place I am referring to is ancients temple. Is that hardcore only ?

You sure you watched him play d2 and jot path of diablo?

There are three red portals you can take in A5 (in frigid highlands, arreat plateau, and frozen tundra).

It takes you to a small map similar to the portal for Uber Izzy (furnace of pain).

Perhaps they were playing path of diablo. What the hell is parh of diablo? They looked identical