Are you regularly backing up your iPhone with iCloud backups or iTunes backups on a computer?
If you still have a backup of the iPhone from the time before you deleted the videos, you can recover photos and videos by restoring the iPhone from the backup. Restore your iPhone, iPad, or iPod touch from a backup - Apple Support
But you first have to make a current backup, so you can revert to the current situation after restoring the iPhone from an older backup and saving the recovered. videos elsewhere, or your current data and documents will be lost.
However, an iCloud backup will only include the videos, if you have not been using iCloud Photos. If iCloud Photos has been enabled, your photos and videos are not included in the backup, and there is no way to recover them from iCloud or your backup.