Plus bikes vs. Fat bikes

I saw a BikeRadar video showing a comparison between 2.35" tires and 3" tires. The 3" tires won. Then I read a few messages from people saying they beat their personal records by going 27.5x2.8" instead of 29x2.35".

So, if Plus bikes have an advantage, how do they compare to 4" tires? I'm asking because I did a search on Youtube and wasn't finding what I was looking for.