The 720p WEB-DL is the most convenient intersection of quality, size, speed, and compatibility. It is the "Goldilocks" hack.

When you download a WEB-DL, you are getting the exact file the streaming platform serves to a paying customer, minus the DRM encryption. Why is 720p considered a "hack"? In an age of 4K televisions and 8K upscaling, 720p (1280x720 pixels) seems primitive.

A 4K HDR file requires a powerful graphics card, specific codecs (HEVC), and a compatible display. A 720p file, usually encoded in H.264 (AVC), will play on a smart fridge. It will play on a decade-old iPhone. It will play on a car's backseat entertainment system.