Marty,
From what I saw on the video, Brent stayed to the inside because he hadn't fully passed Bill. Once they started braking for the corner, it appears Brent got on the brakes harder than normal to give Bill room to go by and likewise, Bill seemed to slow thinking Brent had the ability to overtake and would complete the pass on the inside. Unfortunately two gentlemen racers were both giving the other some room and you got caught up in the mix, hence the slower corner speed that lap. No one's fault in my opinion as his braking took you by surprise and the subsequent lockup and tap was the result. Glad to hear that the incident had no effect on the performance of the cars involved.