There are a few methods a teacher could go through to screencast themselves to have a video tutorial for a student. You could capture your screen using your Zoom Pro Account. Make sure when you sign into zoom.us the first time that you click "Sign in With Google" to get your Premium features.
Zoom can archive with "Cloud Recordings" if you want to archive any Zoom session that had students in a live session, or you can use it to archive just you doing a screencast. If you wanted to setup a playlist of your zoom recordings, THIS VIDEO shows how.
I use Screencastomatic to create my videos (there is a free version but I pay $36 a year for a license. It has many editing and green screen tools.
There's nothing wrong with screencastify which many of us used for free during last March. It's still a great tool and works well on a chromebook if your students need to capture their screens for less than five minutes.
AudioTools
Music Library of Youtube: https://www.youtube.com/audiolibrary/music
Freeplay music (you must login to save a file and assign how you plan to use the file)
Youtube to Mp3 Allows you paste a youtube link which captures just the audio. Note: many youtube artists have specified with youtube whether their music is ok to use. If your video is to be completely public please keep this in mind as not to break copyright.
Clyp.it (must be logged in to save a file) this can be used to make an audio sample that is recorded by you.
Vocaroo.com (you do not have to be logged in to save a file. There are options to download in different formats and a QR code option.)
TwistedWave.com (you do not have to be logged in to save a file.) This resource allows you to record yourself, then go to file-save--google drive.