why is hamlet so moved with hecubas story given by a travelling player? how does hamlet describe himself as a revenger in the soliloquy at the end of scene 2

Hecuba is the opposite of his mother. She cries and screams over her dead husband where as Gertrude jumps into the sheets with her husband's brother. In the soliloquy, Hamlet chastises himself for failing to be moved by his predicament, "That have a father killed, a mother stained". He marvels at how a player may shed tears over a mere story but he can't man up and take revenge for his real father.