That's a complicated question. Copyright infringement occurs when someone infringes one of the exclusive rights that are given under the act, which includes the right of reproduction, the right of communication to the public, etc.
Whether or not something constitutes an infringement depends on the specific circumstances, and that's what makes copyright very complicated to manage. Even if there's an instance of someone making a copy—someone has appropriated someone else's work and, say, includes it in a video—there are also very legitimate reasons that they're permitted to do so, because there are various limitations and exceptions that exist under copyright, such as fair dealing, for example, that permit limited uses of the work, and there are also a number of specifically enumerated exceptions that exist under the act.
Then even if, on its face, it's a copyright infringement, whether or not it falls under the exceptions is very much subject to the context. That can make copyright very challenging to adjudicate.
A case in point is content ID. It is again an extremely powerful copyright management tool. It is very good at detecting copies of a work that has been uploaded and given to us as a reference file, and then applying automatically a policy the rights holder has selected—block, monetize, or track.
It doesn't do that in a terribly nuanced way. The rights holder tells us how they want to set this up. They can set it up on a territory-by-territory basis. They can set it up so that you can use five seconds of the work, but you can't use 30 seconds, but it can't determine whether or not an exception applies.