1.Polly spent much time （to watch） the video plays
语法：spend some time in doing sth.所以应改为：
Polly spent much time watching the video plays.
2.I an sorry i can not find your dog .Maybe it,s not (live)
live用作形容词表示现场的,直播的,用作动词表示生活.而alive才是活着的意思.所以应该改为：
I am sorry I can not find your dog.Maybe it's not alive.