personally, an with my lack of any mechanical training, it sounds like something engine related
the sound gets louder and faster as rpms increase, and the sqeaking is intermittant, and doesn't sound like a belt.
as far as the A/C compressor is concerned...i wasn't running A/C at the time (ilive in western washington, it doesn't get much use
), if that makes a difference.
Alternator was just changed, but it was a rebuild. when you say " blew up," how literal are you being? there were no exploding-type noises, no shrapnel, and nothing that sounded to me like a belt flying off into infinity