Option 1: Use built-in screen recording on iOS 11 and above
Option 2: Use QuickTime if you use iPhone and Mac
Option 3: Apowersoft Phone Manager for iPhone and Windows PC/Laptop
Option 4: You can also use other devices to record your iPhone screen.
Things to keep in mind
In Testlio, a video screen recording attachment has to be less than 10 MB and in .mp4 format. That means you will need to convert and reduce the size of your video files before you attach them to your bug report.
In case you will need help resizing and converting video files, use Tips from the Community article.