A recently released video of Ray Chen playing Clair de Lune shows what appears to be a strange flat object on the violin bridge.
I thought originally that it was maybe part of the tailpiece or chinrest, however when he moves around, it does look like it's part of the bridge.
My thoughts are:
- Some form of microphone? (Microphones typically go near, or under the bridge, unless this is a type I am unfamiliar with)
- A strange mute? (Normally a concert mute is a small round rubber object that is on the middle two strings, and why would he use a mute for a piano duet?)
Here is a screenshot of the video: