Cause it is Friday here.
The horn soloist at 4:22 is Alan Civil, who played the horn solo on the Beatles 'For no one' and took over Denis Brain's chair in the BBC symphony.
Perhaps it is a reflexive grimace at the finale around 6:53, but I'd like to imagine that after he has just gotten the orchestra to hit those stacked chords staccato(!) he was thinking back to when he was playing those chords on a piano for Diaghilev in St. Petersburg, wondering what the future would hold for him. Or not, I've never been able to keep track of the various revisions of Firebird and so I'm not sure if the finale was added later or was in the original version. Maybe he was just thinking 'damn, that sounded nice.' Hope you think so too.