For starters, take to note that any motion picture is primarily a commodity that should be sold. So what is online and available for viewing and downloading is already an illegal resource. If it doesn’t embarrass you, act at your discretion.
The first and proven way that has become widespread is the use of torrent trackers. Someone from the film’s fans bought a licensed disc with great quality, copied it and can now hand out to other users. You can find the desired file from the search bar on the site, and your choice will open several sizes ranging from CD to Blu-Ray. Don’t forget that to work with trackers you need a torrent manager, for example, µTorrent.
Alternatively — downloading the movie via direct link from the filesharer. However, in this way you do not receive a guarantee of the quality of the downloadable file. You can find links to direct download using a search engine, such as Yandex. If you download a file with the extension *.exe, it’s not a movie, but most likely a potentially dangerous program.
There may be marks next to the file, pay attention to them: CamRip (Cam) is the worst quality, filmed by the camera in full cinema, so often viewers’ heads are visible, TS is a good camera recording in an empty cinema, sound recorded directly from the cinema equipment, SCR is an acceptable screen recording quality, DVDrip (BDrip) is a copy from DVD or Blu-Ray disc, HDTVRip — copied from HDTV (cable TV) broadcast.
On social networks, for example, VKontakte also put up copies of films, sometimes in good quality. The plus is that the quality you can appreciate in real time. However, downloading streaming video will require a special program such as VKSaver.