I just beat Radec [Elite Difficulty] using this method, except instead of using the magnum I opted for the knife instead. It seems to have been quicker, but more dangerous seeing as he's on fire and if you get too close you can get burnt.
But yeah... thanks for posting the video. It was inspirational and helped me pull through.
After months of being stuck in that room on Elite, it was extremely satisfying to burn and stab my final enemy to death!