Legally, this is a grey area. Most streaming apps (Netflix, Hotstar) block screen recording via DRM (Digital Rights Management). If you use a third-party screen recorder, you are bypassing copyright protection, which violates the app's terms of service.
If you want to watch Hindi serials without an internet connection, these are your best options. You won't keep the file forever, but you can watch at your convenience. Free Download Hindi Tv Shows
However, a quick Google search for "free download Hindi TV shows" leads you down a confusing, often dangerous path. While the desire to save data and watch offline is understandable, many free download sites operate in a legal grey area—or outright illegal piracy. Legally, this is a grey area