Thanks for all the info... it went a little bit beyond what I can understand (ssamadhi97's answer seems to find consensus, but I >think< I managed to spot it as it flew really high above my head ).

The original source is supposed to be SBD, but from what you say someone did a conversion somewhere and/or resampled the signal and totally botched it... sad, really, it's a magnificent show. I guess I can consider it as NOT MP3-sourced but lossy in other ways, right?