Are you using swayidle? It’s supposed to automatically keep the screen on when there is full-screen video playing. It’s the same in Gnome: you generally don’t need caffeine if a full-screen video is going.
How are you playing videos? Maybe the player doesn’t correctly implement the idle inhibit protocol. Or if you’re using sway bindings to make the window fullscreen instead of using the app’s own fullscreen mode then maybe the player doesn’t know it’s fullscreen, and doesn’t set up the idle inhibit.
If you do want manual idle inhibit control, if you use Waybar it has an idle inhibitor module that mimics caffeine. If you don’t use Waybar there is a little Python script you can run. Kill it when you want to stop inhibiting idle. actually wib looks like a better option
My conclusion after researching this a while ago is that the good options are Borg and Restic. Both give you incremental backups with cheap timewise snapshots. They are quite similar to each other, and I don’t know of a compelling reason to pick one over the other.