There is a whole genre of 4 part close harmony videos on youtube, created by guys working alone and overtracking themselves on their computers and webcams. This guy had the help and support of a cappella comedy group Moosebutter (from Provo, UT), who originally adapted and recorded the arrangement.
In fact, the young man comes clean in the video notes and acknowledges its not him singing, but he’s lip synching the moosebutter recording.
Further investigating shows that the arranger makes the TTBB sheet music available for free! Hey Makeshift guys: could this be our next “BohRhap”?