I love karaoke. DO you?
Yes, karaoke is often implemented by recording engineers in reference to version of recording with instruments too.
Do they have to record things separate from what they use in the originals? 
There are many artists that will often record and can't afford a band/orchestra so they will use karoake recording.
That is very interesting. I have not heard that, but it makes sense.
Some people think it's the same thing as lip synching but it isn't. That's where the singer will mimic a song that has already been made and already has a lead vocal.
Is karaoke popular outside of the US too?
. The primary difference between Karaoke and sing-along songs is the absence of the lead vocalist.
Sing-alongs (present since the beginning of singing) fundamentally changed with the introduction of new technology. In the late 1960s and into the 1970s, stored audible materials began to dominate the music recording industry and revolutionized the portability and ease of use of band and instrumental music by musicians and entertainers as the demand for entertainers increased globally. This may have been attributable to the introduction of music cassette tapes, technology that arose
and recording original material in a Los Angeles studio. The members bonded over a shared love of afrobeat including Fela Kuti. 
Describing his role in the sessions as "conducting", Yorke would show the band electronic music he had created and they would recreate it with live instruments. He said: "The music I do on my laptop is so angular. When you get people to play like that, it's so peculiar ... One of the things we were most excited about was ending up with a record where you