That’s all very well and good but as you’ve seen after 30 days not only does the student lose their game, but so do you, so that messes up your lecture and links anyway.
Some students, but perhaps not all, I’n sure would be interested in having their portfolio available for longer than 30 days, indeed you talk about portfolios and artificats in the How to get a job in the Games Industry course, so showing them how to use a service that doesn’t retaining their games seems to be at odds with that.
I know it would be a re-record, which isn’t favoured, but perhaps showing the process of uploading to ShareMyGame.com for simplicity and advising after 30 days it gets wiped and showing one or two other services like Itch.io / GameJolt would be really valuable to students and it would also enable you to then leave your course games on your official itch.io page which would then be retained and make sense with regards to the lectures content.
Or - annotate the video and state that after 30 days your game got wiped and remove the link?
Or - remove the 30 day expiration on ShareMyGame.com across the board and take a hit financially on storage space for all of the clones of the same game where people are not interested in keeping a portfolio.