Searching for or downloading movies from sites like Isaidub carries significant risks:
The Tamil dubbed version is widely available on regional streaming and download platforms, allowing Tamil-speaking audiences to enjoy the sci-fi action in their native language. Where to Watch
Despite the legal issues, the existence of a "Tamil dubbed" version on such platforms indicates the lasting popularity of the Alien and Predator franchises in regional markets. Alien vs. Predator (2004)