The Muppets: A Celebration of 30 Years - finale question

[minor muppetz]

Okay, here's something I've been wondering for awhile, and I'm not sure how likely I'll get an answer (but maybe somebody who worked on the special will be interviewed for The MupetCast or Tough Pigs and be able to answer...).

Anyway, at the end of The Muppets: A Celebration of 30 Years, the Muppets all sing The Rainbow Connection, and when there are close-up shots of characters, the characters shown in close-ups can be heard more clearly. Does anybody know whether for these scenes the perofrmers were instructed to talk in certain voices for certain lines, or if the performers recorded the song first, and then when it was being taped they also sang as their characters live on the set?

 

[Colbynfriends]

Thats a good question. I thought whenever they did a song they would all sing in one characters voice (Jim would do Kermit, Frank would do Fozzie) then they'd do it in diffrent voices (Jim would be Dr. Teeth, Frank would do Miss Piggy) and they'd keep going like that untill most or all of their characters voices were in the song.