When Apple released the iPhone 11 and iPhone 11 Pro in 2019, it redesigned the stock Camera app on these devices to make the most of their hardware and also to add new exclusive features. One of those features was QuickTake, which allows users to shoot video without switching out of the default photo mode.
On iPhone 11 and later models, you can record videos without even switching out of the default photo mode. To capture a quick video, just press and hold the shutter button, then release the button to stop recording.
To keep recording video without having to hold the button, slide the shutter button to the far right. The shutter will stretch elastically under your finger as you do so, and a target padlock icon will appear.
When placed on the padlock, the shutter button will remain located there for as long as you shoot video. You can also tap the shutter to take a still photo during the recording. When you're ready to stop shooting video, simply tap the record button below the viewfinder. Note that QuickTake video is limited to 30fps.