Browser extensions are limited by a "sandbox" that prevents them from writing large files directly. The Companion App

: As of version 10, the developer has shifted away from traditional keys for many users, instead linking purchases directly to your email address for easier restoration. How to Get a Legitimate License

Many users don't realize that the browser extension is just a "detector." To download "Hot" (encrypted/4K) streams, you must install the (DownloadHelper Native Client).