I suggest downloading the MX Player app from the Google Play Store or Apple App Store. You can then search for "Plan B" and download episodes directly within the app for offline viewing in high definition safely.
Within the MX Player app, you can usually select video quality settings (such as High/720p) and choose your preferred audio language if multiple are available. Why Avoid Unofficial "720p MP4" Downloads? Plan B S01E04 Hindi 720pmp4
It looks like you're searching for a guide to finding or watching in Hindi 720p MP4 format. I suggest downloading the MX Player app from