Uncertainty in pricing is terrible so in my view avoid the how many users watch your tutorial pricing. It can also inhibit usage which you don't want.
I'd charge based on number of tutorials. For upto 3, it's free but your branding is there. For upto 20 tutorials on your site, it's $30/month or something. You get the idea. This ensures if some massive site is using you for hundreds of tutorials, you get paid for the value you're delivering.
Of course, pricing is a dark art so take these thoughts with a grain of salt.
Really appreciate the advice. I agree we don't to introduce unnecessary uncertainty. Thanks especially for the hypothetical tiers that is great to have from an outsider.