sylvan You might probably not get an official statement on this. I recommend to read SLR's Terms of Service/Use to find out if there is a clause that prohibits downloading if there is no button.
For comparison: The Youtube terms prohibit any downloading, with the exception of content for which there is an explicit permit or that is not copyrighted.
It can be assumed that absence of a download button means that the original content providers do not want that their content is made available for downloading on the website. But this is an agreement between the content providers and the website. You most probably have not signed any agreement with the content providers, only with the website.
