Well I think for your use case it's good to have a headless cms as it will generate the rest api or graphql whatever it may be and it will be easy for the user to upload the videos nd other training materials. It can be used for the e-commerce apps and websites and will do the job in those cases. I don't think there will be any problem in using it but the point to be noted is how you handle the user roles.
If you want to handle roles in any webapp you should make it with some Backend Technologies as it will save the cost of deployment as the Headless CMS' can cost you more than 10 times the cost of a node based app and you will mostly use 3rd party services for static assets and those are also limited.
Better use s3 for static assets and AWS, GCP or Heroku for hosting the REST API and Netlify for Front end may be.
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