For at least a good chunk of the run, the only part of the Scrabble intro that was live was the clue itself. Even "It's a 6 letter word, and the clue is..." was pre-recorded, as evidenced by some masters where that's clearly in one channel, and the clue read is in another. But there's a YouTube clip below where a contestant talks about Charlie Tuna, and they cut to him. There's also episodes where Chuck makes light of the prize about to be described, and Charlie reacts directly or laughs. My favorite from the mass posting of Scrabble on YouTube was during some special week, and as Chuck tries to throw it to the prize, Charlie dryly instructs him on the mic to "open the envelope first" for the home viewer tie-in.
It's been covered here before that much of SOTC with Jay Stewart ended up pre-taped because of his condition at the time, with only the Fame Game reads being live.
-Jason