Unfortunately the original posting doesn’t say how this effort to organize a virtual performance came to be, but we can assume that it wasn’t something that was recorded live (I’m not sure it’s actually possible to get 206 individuals into a single video chat). Regardless, the editor of the piece deserves a lot of credit for putting the whole thing together, because whether it was a job requiring stitching all of the videos together, or stitching a collection of group sessions, it still must have been an effort.
Article source: https://www.cinemablend.com/news/2494406/watch-young-musicians-play-the-avengers-theme-song-from-isolation-and-try-not-to-cry