Video proof has long been established in football. For the question of whether the ball was behind the goal line or a player was offside, stored information is used to establish the facts. In patent proceedings, too, prior art knowledge that has been published on the Internet or in online databases has been used for a long time and there are established rules and principles for dealing with Internet disclosures in the form of guidelines of the offices and case law of the competent court bodies. At present, however, applicants and owners of technical intellectual property rights are increasingly confronted with forms of Internet disclosures which have been developed only recently or which have not yet been cited routinely as prior art. These include websites for the distribution of videos and photos, contributions from social networks, blogs and discussion groups, wiki pages, etc. whose contents can not only be read, but also edited and changed directly in the web browser. Documents from such sources are also state of the art. However, it can be much more time-consuming to determine the date of publication and the reliability of such sources. This article highlights some important aspects in determining the relevant date of an Internet disclosure and the questions of evidence related therewith.