"LaLCS" stands for "Live and Live Combined Stereo", which means that the left and the right sides of the video come from two different LIVE performances.
In this case you can enjoy the live cover by Ariana Grande of George Michael's classic song "Last Christmas". On the right side the Rockefeller Center performance from 2013, while on the left side at the Michael Buble's Christmas from 2014. Links:
   • Video  
   • Video  
   • Ariana Grande - Last Christmas LIVE a...