I'm pretty sure he's actually playing; he's an excellent violinist and he's playing music that a good amateur orchestra can play well on one rehearsal, so it's not as if playing it is really any work for him. It's all more about the showmanship than the playing, anyway. Everything is amplified, of course, because there's no other way the orchestra would be heard at his enormous outdoor concerts.

He has one of Stradivari's earliest violins, and probably uses it when performing in smaller indoor venues, but I seriously doubt that it's the instrument he plays in his bigger concerts. I would guess that he plays something substantially less expensive in larger venues.

Very few pros play their "good" string instruments in outdoor or amplified settings. The risk of damage to the instrument is higher, and differences in tone quality are not as noticeable as they would be in a concert hall with state-of-the-art acoustics and a near-silent audience. Many pros use their best instrument when playing in a concert hall, but also have a much less expensive instrument (often a high-end workshop instrument) that they use for outdoor and/or amplified gigs.