Is a person considered an infidel if his brother watches films containing explicit mockery of religion on the home computer, knowing that he was the one who installed the Windows operating system and programs, and is his prayer accepted in this case, and what about his purchase of a satellite dish receiver that displays the same content?

There is no room in what was mentioned to question disbelief (kufr), for whoever performs such actions, their disbelief is not doubted except by one afflicted with waswas (obsessive whispering). The questioner should strive to cure their waswas by ignoring it and casting it aside, because waswas is a severe illness. The questioner's fear and aversion to mockery is evidence that they are not among those who mock religion. Satan is trying to drag the questioner into a grave sin, which is abandoning prayer. Therefore, one must beware of waswas that could lead to that, and if a prayer is missed, repent to Allah and hasten to make it up.