When the content provider offers the content for free, the viewer obtains the right to consume any portions of the content they want for free. If a website want

When the content provider offers the content for free, the viewer obtains the right to consume any portions of the content they want for free. If a website wants to require the viewer to consume all of the content when they view it, they can do that in their terms of service, though it might not be legally enforceable. Most sites don't.