Explain

explain.mit.edu is like Youtube but for blackboard-based education videos.
I've made the mistake of not charging users. It's confusing to me, because you see so many "big name" companies being free, such as Facebook . Moreover, charging for education content seems to be frowned upon.

But after 4-5 years of almost no growth and 0 users, I started to really listen to YC's advice "you need to qualify your customer, don't be afraid to walk away if they don't have the problem" (but of course relentlessly pursue the right customers once you qualify them).
Another YC video: "the 1-3 seconds of reaction on their faces when you ask them to pay, tells you almost more than anything else for whether you solving a problem"

So I iterated to a marketplace model where college students can subscribe to each other for help (still using blackboard videos), so a really great "Youtuber" can charge a small price from many classmates.

I opened my own shop for one of the classes, and on Wednesday I got a text notification saying someone had signed up for the $1 discounted trial (so never offer free trials, but offer discounts and refunds is what I heard). I thought it was a mistake, because when I checked Venmo there was nothing.

It turns out my Venmo wasn't displayed - later Andrei sent me the $1 Venmo payment, and I will remember that forever.