I think there's confusion between video and e-book formats. The user might be looking for a way to access Hindi MP4 content on mobile devices (hence "mobi") and "best" refers to the best sites or methods for that. They could be referring to hindimp4.com as a website for downloading Hindi MP4 movies, and now want the best MOBI (mobile-optimized) version of that site or content for mobile access.
: Downloading copyrighted movies from these sites is generally illegal. Official streaming platforms are the only licensed way to view this content . Recommended Legal Alternatives hindimp4 mobi best
So the structure would be: