DESCRIPTION:
"LaRCS" stands for "Live and Record Combined Stereo", which means that on the left you can hear a live performance, while on the right the clip version.
Regarding the current video, you can enjoy "Leave A Light On" from Belinda Carlisle (ex Go-Go's): on the right side the official music video clip (tempo adjusted), while on the left side a concert version from 1990 (Runaway Horses Tour. (The concert version is live over a pre-recorded vocal). Links:
http://www.youtube.com/watch?v=JgIuWDxgWjw
http://www.youtube.com/watch?v=2Js_WUsXpxg
http://www.youtube.com/watch?v=vfyTToBawG0