For those who watched, the group with the beatboxer/vocal percussionist was the group Rudy was in. (Blake, the VP guy, is an a cappella guy from Seattle, so it's not surprise that they were working together.) The group ALSO did a great job and showing off the type of stuff that I've been producing for the past 4 weeks.
And for the record... I AM ashamed that I'm actually watching AI this season somewhat live and not days later on the TiVo.