Where can you access the videos?

This varies depending on which camera system you are using. There are some brands that offer their own app where you can not only follow the live image but also watch recorded videos. An example of this is eufy.
On the other hand, there are also cameras that can be integrated into existing systems, such as AJAX, where any IP camera that supports the RTSP protocol can be integrated.
Some cameras can also be easily connected to a hard drive, where the video recordings can be stored completely.