A man is sitting in front of a computer monitor holding a keyboard and looking at the camera.
There is a man looking in front of a computer monitor because he is video chatting.
It is never states in sentence one that the man is actually video chatting. He could be playing a video game maybe instead.
exists e1 e3 e2 x1 x2 x3 x4 x5 x6.(n_camera(x6) & for(e1,e3) & at(e3,x6) & Actor(e3,x1) & v_look(e3) & for(e1,e2) & Theme(e2,x5) & Actor(e2,x1) & v_hold(e2) & n_keyboard(x5) & in(e1,x2) & of(x2,x3) & n_monitor(x3) & of(x3,x4) & n_computer(x4) & n_front(x2) & Actor(e1,x1) & v_sit(e1) & n_man(x1))
exists p1 p2 x1 x7.(n_male(x7) & exists p3 s1 x8.((x7 = x8) & n_chatting(x8) & a_video(s1) & Theme(s1,x8)) & because(p1,p2) & exists e1 x2 x3 x4 x5 x6.((x1 = x2) & in(e1,x4) & of(x4,x5) & n_monitor(x5) & of(x5,x6) & n_computer(x6) & n_front(x4) & Actor(e1,x3) & v_look(e1) & (x2 = x3) & n_man(x2)))