Google has updated its learning video structured data documentation to no longer require the text field for Problem walkthrough videos and clips, now, it is just recommended.
So if you use this structured data, you no longer have to use the text field, but Google does recommend it anyway.
You can see the help document here and dig into it, but you will see the text field no longer says required, but rather it says recommended.
Learning videos are videos that are aimed at students and teachers to discover and watch educational videos. They include educational level and concepts and skills covered in the video. There are learning videos structured data to go along with these learning video rich results.
Here is what Google posted in terms of what these learning videos can look like:
Forum discussion at Twitter.
