Since "Altadefinizione" is a well-known Italian streaming site, 🎬 Flatliners - Linea mortale (2017)

The term "Altadefinizione" often appears in the file names of pirated content. If you are looking to watch the movie safely and legally:

Ellen Page, Diego Luna, Nina Dobrev, James Norton, and Kiersey Clemons. Kiefer Sutherland also appears, reprising a role (though under a different name) from the original film. Genre: Sci-Fi / Thriller / Horror.