(non-copyright-infringing)

The most secure way to "download" for portable use is through the offline viewing features of official platforms. Check services like Hulu, Disney+, or Netflix (availability varies by region). These apps allow you to download the movie in 720p directly to your device's internal storage.

These files require minimal processing power to decode, preventing battery drain.

In the context of digital video, a "portable" format typically refers to a file that requires zero installation of heavy external codecs or specialized media centers.