Watching your child from moment to moment is far more important than going over footage from previous nights, so baby monitors don't usually make a big deal about saving video for later, whether using built-in storage or through a cloud service. They can take snapshots and short clips when they detect movement, but they won't offer time-lapse videos of entire nights at once, or let you page through hours or days of footage. Those features are useful for identifying burglars, but they don't really help you watch your child unless you're in a Paranormal Activity sequel.
If you sleep in the same room as your baby or live in a small enough space that you can always hear or see what your baby is up to, you probably don’t need a monitor. Otherwise, most parents enjoy the convenience a baby monitor provides—instead of needing to stay close to the nursery or constantly checking on your child, you’re free to rest, catch up on Netflix or get things done around the house during naptime. Monitors can also double as a nanny cam to keep an eye on your child and their caretaker.