They were just showing their ability to move around. Queen got rave reviews after Bohemian Rhapsody.
At least on Bohemian Rhapsody the group was one with the song; they played the instruments and did backing vocals. It was Queen.
Beth, on the other hand, was sung by Peter Criss, with session musicians on piano and strings. Criss was backed by a tape in concert. The other members of KISS had zilch to do with the song.