They suspend accounts (after months if not immediately) that abuse serving disproportionate amount of non-HTML content, videos specifically. However there is still ambiguity (or lack of detail) in their terms if you can use their Workers, a paid FaaS, to stream blob data.
I thought this only applies to their free accounts, and that they have no issues with serving any size files as long as you pay them.
I've only heard stories of people getting terminated over abusing their CDN like that, and I don't fancy being next.