In trying to make sure I am prepared for upcoming flight(and I understand aircraft isn't known for sure until 48-24 Hours before departure etc), I have called into United to ask general questions about in-flight amenities. Specifically the on-board Wi-Fi and separately the Personal Device Entertainment feature. I would prefer to watch movies on my laptop(which is not a mobile device - right? - nobody at United seems to recognize this). They can't seem to confidently tell me that I DO NOT need to purchase wi-fi nor download any app prior to boarding. Am I to understand it correctly that I DO NOT need to purchase wi-fi nor download anything prior to boarding? I believe that once on board I just need to connect (and something about a 'plug-in'). I am amazed that no one at United is able to answer this simple question.

Any advice or experience would be greatly appreciated. Thanks