There are two types of IP addresses, a local, private address, and a public , global address. A public address is the one that you can use outside the local network to connect to it, and its private address is what is used on the network. Private addresses start with 10., 192., and 172/173.
A camera is usually part of a network, either saving the feed to a local computer, and/or networked with other cameras. This way someone is able to monitor the device. However, in recent years smart cameras have become more popular, growing with the IoT boom. These cameras can be wireless, connecting to a local access point, they can store data on the device itself, usually by using an SD card, and can be accessed over the internet through a web portal.
The security issue with IoT cameras is pretty obvious, if you can gain access to its web portal, you can potentially brute-force the password, (many people don't even change the default login details, a quick google of the camera brand can get you that info), or if you have a wireless card that provides monitor mode you could perform a deauth attack, and get it to connect to your own network, either to gain details about the device itself, or the contents of the feed.
If the camera is not a smart camera however, it usually means that it is on a wired network, and only accessible by gaining access to the machine that is monitoring it. This presents its own, separate series of challenges.
So to answer your question, we have two main scenarios, which depend on whether the camera is wireless or not. If it is wireless, then yes you can potentially gain access directly to the camera itself, either through a deauth attack or over the web. If the camera is not wireless, then yes it can still be accessed, but that would require gaining to the machine monitoring the camera(s).
Both of these methods have legal implications of course, so check with local laws and gain permission where necessary.
If you need more info on anything leave a comment and I'll update this response to reflect further questions.