While watching a downloaded video for personal use is rarely prosecuted, distributing "unlocked" content or using tools to bypass DRM is a violation of the Digital Millennium Copyright Act (DMCA) in the US and similar laws globally.
For the user, the "Download" is an act of reclamation. In an era where digital media can be deleted or edited by the provider at any moment, downloading a video is the only way to ensure digital permanence Practicality: