Well I'm thinking the same, but then I'm not sure where to put this video (ignoring the sound track) on a scale from drunken singing to obvious Nazi salute.

Maybe i don't know enough about Bierzelt culture. If they were singing Hölle, hölle, hölle or Atemlos, would you notice the (right) arm in the air? The arm movement seems unnatural (if the intention was signing with arms in the air), but this could still sort-of pass as not 100% Heil Hitler.

The band chose the song, for sure, that's questionable. The event organisers should not allow this to happen. But the guests, should they leave? Sit down quietly and wait for the next song?

I could be in that tent and not recognise the song. Not my kind of music.

I could see people innocently copying the movement of others. It may be a tent full of Nazis, scary, but the video does not proof this.