There’s a website that has numerous shiurim that they allow people view 30 minutes amonth for free.
If you want to watch more they have for different amounts of monthly donations subscriptions.
Can I use masser to pay for the shiurim since they consider a donation?
This sounds to me like a regular business, that charges for their services, and the more you pay, (which they are calling a “donation”) the more services you can get. Therefore essentially you are paying in order for you to learn torah. This should not come from maaser money, because we don’t use maaser money to pay for the mitzvos that we have to do. If you would be paying for someone else’s subscription, then it would be like paying for them to learn torah, and of they need the money it would be considered tzedakah, but not for your own learning.
Best wishes and a gmar chasima tova
Conversation with R’ Y. Feinhandler shlit”a, author of B’orach Tzedakah .