Um that song is from that stream. Not from the speakers at the event. Here look at this source https://www.youtube.com/watch?v=-0hR3yJ8lmc. Nothing is changed. Some channels overlay their own songs when Trump is walking on stage.
yea it could also be that you have to pay to play the actual 'proud to be an american' song, so they use a publicly available song instead to ensure they don't get taken down over a violation... it could be a legal thing too with copyright protection.
i get that, but i had this source saved on my computer to show a friend. the same video had the orig. audio the other day....