Can I use "bad memory" when I talk about the unpleasant memory? I'm confused the meaning of "bad memory" because "memory" seems to be used as a ability to memorize something.
Excellent question. The phrase "bad memory" has two meanings that are recognisable by context. The first, as in the video, means that someone is not good at remembering or memorising something. The second meaning is that someone has had a bad experience in the past. Ex: I have a bad memory and now I can't remember where I parked my car. Ex: I have a bad memory of swimming in the ocean.