How can I see the captured pieces and material count?
Underneath each player's username you can see which pieces they've captured. If there is a material imbalance, this will be reflected with a number next to the pieces of the player who has more material left on the board.
Only the player who is ahead will have the + number, the other side will show no number.
Note that in the above image, I (Dave) am playing with the black pieces. The white pieces under my name are the pieces that I have captured.