The TheoPlayer video download link is generated using a combination of technologies, including HTML5, JavaScript, and server-side programming. When a user requests to download a video, the TheoPlayer library communicates with the server to initiate the download process. The server then generates a unique download link, which is sent back to the client-side, where it is processed by the TheoPlayer library. The library uses the generated link to download the video, which is then saved to the user's device.