This is the part of the Service most likely to touch someone else’s personal data, so it is worth being precise.
You choose the URL. We load it and store the resulting image or video, along with the URL itself in your usage log. A capture can therefore contain personal data belonging to people who are not our users: anyone whose name, photograph, or details happen to appear on the page.
For that captured material you are the controller and we are your processor: we process it only to carry out your capture instruction, we do not analyse it, index it, or use it to train anything, and we do not look at it except where we must investigate a credible abuse report or a legal request.
It follows that you need a lawful basis for the captures you make. The acceptable use clause in the Terms sets out the limits, and it is not decoration: capturing pages behind a login, or pages whose purpose is to expose private information, is a breach of contract as well as, quite possibly, of data protection law.