I'm not sure its fair or accurate to project PC piracy levels based on a comparison of console vs. PC sales. He suggest that he didn't believe the piracy rate on PC was 70% until he saw that COD4 sales on console outsold the PC 10 to 1.
Among the reasons other than piracy that COD4 on console outsold the PC:
1. The lead development platform was Xbox.
2. The game was marketed primarily as an XBox title.
3. There COD series died on the PC after COD2 (most people think of COD as primarily a console title, IMO).
4. The PC edition doesn't offer PC-specific improvements.