Good point, Bob. It's a very subjective question.
If somebody learned guitar, and was a proficient guitar player, and was then asked if playing the piano was easier, then it's obvious what the answer would 'usually' be. It all depends on the skill level achieved with each instrument.
However, this clearly wasn't really the point of the video. The video showed two virtuoso performers sharing their skills. It was entertainment. ( I think the guitar won -

)
A fun and entertaining video, actually. Clearly a set up
