Pilot with Hypoxia talking with ATC - this ends well

The pilot is compromised by hypoxia but still able to declare an emergency and talk to ATC. He descends to 11,000 MSL and regains control.

http://www.liveleak.com/view?i=b97_1409965702

Listening to this refreshed my awareness that the effects of hypoxia can often be incremental and progressive, that some function may be retained temporarily, and that descending to a lower altitude may restore a pilot's function quickly. Basic facts of course, but good to review and keep in mind at the start of wave season.

So if you hear someone talking like this on the radio, how do you respond?