A screencast is a digital video recording of your computer screen and usually includes audio narration. Screencasts are just one of many different types of instructional videos.
Screencastify Is a Chrome extension. Maximum length 5 minutes. Integrates with Google Drive. Multiple output formats including audio files.
Loom - Is a Chrome extension. No maximum length to recordings.
Screencastomatic - Is a Chrome extension. Maximum length videos is 15 minutes. Requires download software. Stores video on computer device. Run on multiple platforms.