The recommend way to backup your videos stored in the app is to enable cloud storage. This is a Pro feature so make sure you'll have to upgrade if you want to use that feature.
Enabled cloud storage (Pro)
- Edit your timeline (how to edit your timeline)
- Enable cloud-storage for the timeline (do this for all timelines you want backed up)
- It's highly recommend you create an account so you can access your account from another device.
- To restore from backup login with your account and your videos will start to download
It's also possible to backup your entire phone and restore it on a new device the app. Here's an article on how to backup & restore