I think a lot of the time the phase shifting is not by fault of the violinist and rather just how we hear it, even when it's played perfectly in tempo. If you want to avoid that for the listener you kind of need to actively work to make time on downbeats. Sometimes it works better to just let it flow, imo.
Crystal clear tone and vivid use of some brief dynamics contrast. I'm just wondering what concerto did he actually play before tossing off this as an follow-up encore ?