I think he sang totally differently at this gig. Just compare his voice there to his voice at Edinburgh or any of the Opera Tour gigs. To me, the whole tone of his voice was much thinner and was very unstable at this gig. It was probably because of the fact that they were playing to 150,000 people for the first time so I dont blame him! Nonetheless, some songs did sound good but in a lot of them he sounded very off key...almost as if he couldn't hear himself in the monitors... Common examples where he sounds off key and incredibly unstable are: BoRhap Rock Section, Ogre Battle, Sweet Lady, '39, The Prophet's Song, and In the Lap of the Gods Revisted.
I think it's a combination of nerves, the quality of the audio (we either have fluttering or distance affecting the recording), and the monitors on the stage weren't probably the best (which explains why Freddie keeps adjusting his pitch in spots).
As for the thinner voice, I think Freddie had a chest cold (which can affect your power in your full voice range), so some of his higher notes weren't stable, or had little power in them.