For those saying it's annoying to have the crowd sing the first few lines or whatever
Alex probably never even thought that much into it. He probably heard everyone singing and was like "holy shit, they already know the fucking lyrics" and let them sing it. I'm sure he wanted to let the fans have fun too. Plus he was probably and obviously just really stoked on how cool that was for him and the band. Soooo not sure what the problem is
Anyway. Sounds good!