From a recording standpoint, it seems odd that in a live studio, where that orchestra wouldn't have been cheap, there would be a guy whose job it was to yell out lyric prompts. Paper was invented by then, so it seems if Englebert was struggling to remember ...
the title of the song(!), then maybe they could have printed out the lyrics for him. If you Google "Pictures of Frank Sinatra in the studio," in most of the image results, he has a music stand in front of him. So it's not like there was any shame in it. (Or at least not any more shame than needing a guy to yell lyrics at you.)
I'm not saying there's
not a guy yelling "the shadow" in the clip, mind you. Who knows, maybe Engelbert had a nephew who needed a job. I can't hear it, though, even after about ten listens, so I gotta wonder whether it makes sense from a practical standpoint. (Either way, this is a fun thread.)
On a semi-related note, as someone who spent many years on 2" tape (I still have one of my 24-track machines here), this is really interesting:
That sounds exactly like they had recorded the whole line
"I will be remembering, the shadow of your smile," and then decided to go back and punch in for a better take of the last half:
"shadow of your smile." Definitely a punch in, since you can hear that he held
"...ring" longer in the first take, since the tail of that is what we're hearing at the punch-in point. (I'm probably not the only old-timer here who can't help but tap my finger when I hear the point where the engineer
should have punched in.)
As someone already suggested, based on the odd reverb cutoff in the punch-in, I think they
recorded the reverb on the vocal track. I'm not positive on that, though.
Lastly,
@Rob, what the heck did you use to isolate the vocal??? That sounds really good!