Obviously those kids could play their butts off… but in this video, they’re obviously older. I dunno if Michael woulda sung those notes at that age… maybe. But Jermaine at least would not sound like he was still 14! And he does. Also, notice how they cut the song off right before the talking part? Also, there are strings in the recording, and there are no string players in that studio. Nowadays you could attribute it to a backing track, but I have my doubts as to whether or not they did that back in the day. What do you think?
I’m no expert, but it looks like it’s lip singing to me. I do know Michael Jackson later would use back tracks and lip sing on purpose; there was video at some awards thing where he literally tossed the microphone aside to dance and the track just kept going with him just dancing. Still though, the guy had talent even if he used that stuff from time to time.