I could have sworn I already posted this, but I sure can't find it. Anyway, it's too good to pass up. If it's a duplicate post, I apologize.
This is Terence McKenna, apparently. That seems rather odd, given his Wikipedia entry, but here's what the video creator says:
As I replied to a similar comment earlier, this speech does indeed stand in stark contrast to much of what he said and believed, both then and later. It's a good reminder that we must guard ourselves against irrationally far more vigorously than we even do others.