This article explains how to use your Chromebook's built-in Camera app to record and save videos. Instructions apply to all Chromebook models, including the Pixelbook.
All Chromebooks come with the Camera app pre-installed. If you have an older device, you may need to download the latest version from the Google Play Store. To record video with your Chromebook:
Select the App Launcher at the bottom left corner of the desktop.
Type camera into the search bar and select the Camera app when it appears.