In an article with Relyonhorror.com, they describe ways that Silent Hills P.T can actually be re-downloaded onto your PlayStation 4. Along with the instructions to do so, they warn players that by following this process, you run the risk of being banned from PSN all together.
To re-download the infamous playable teaser, you must first download and install the proxy app via PSN. Once you have completed this step, simply change your PSN network settings, return to your library and re-download it.
To be clear: in order for this to work, players must have had downloaded the game when it was available. You cannot get the teaser on your console if you haven’t done so before.
If you require any additional information, be sure to check out the attached video.