I had the same problem. I tried to find video, but no results. There's only one video on youtube I've found in which there's a half of the song, and later you have "Every Day/A heart full of love(reprise)". But maybe one day someone find it :)
Dang, Nick Jonas voice is good...I hope someone finds a full video of him singing Empty Chairs at Empty Tables. I only found a video of him singing during the reception scene where the Thénardier's turn up to crash the party.