MX Player (the newer version) has a streaming section with web-series and movies, but you cannot add custom audio to streamed content—only to local files.

No legitimate app does this. Beware of fake "Hindi audio downloader" apps on the Play Store—they are often malware or adware.

MX Player is one of the most popular media playback apps in the world, particularly in India, thanks to its robust hardware acceleration, subtitle gestures, and—most importantly—its ability to handle multiple audio tracks. If you have downloaded a Hollywood movie or a regional film that lacks a Hindi voiceover, you might be wondering: How do I download and add a Hindi audio track to MX Player?

Now, go ahead and enjoy your favorite movies in crystal-clear Hindi audio, perfectly synced with high-definition video, all within the comfort of MX Player.