Under GDPR you cannot mix these two things. They cannot force you to accept conditions that are not relevant to the requested item - if you do not accept the opt-in, they are still not allowed to refuse your access to the monkey video, as there is no meaningful connection between said video and all of your data.
It would be different if you had to pay for something, in which case you would have to agree to share your name, credit card etc. However, they still would not be allowed to share it with unrelated (!) third parties.
> [] I want to see dancing monkeys and for that, I agree to have all my data shared with unnamed third and fourth parties indefinitely.
See? Everyone clicked that :).