Is the developer a criminal organization? It downloads the video to developer's server, not to your hard drive. Seems like some porn site owner found an easy way to get you download videos for him.

It's waste of time anyway. Tried to download a video, 6 times loading interrupted before it finished. 3 times it finished, but Firefox crashed twice when clicking the save button, and third time the save didn't work. Left clicking the save button just flashes, nothing else happens. Right clocking the save window opens, but nothing will be saved. If you open the Firefox download manager (CTRL+J), you can see the save doesn't progress at all: stays at 0Kb.
How about cancelling the saving in download manage? Surprise: that doesn't work either. The downloads stay in Firefox download manager... probably until next browser restart.

It's simply useless on Win7 (M Firefox and MS Edge as well). It was never useful when others ("Video DownloadHelper" or "Video Downloader Professional") failed to download a video in the first place.

it loads 8 seconds of video and the series is 45 minutes every 10th file can be downloaded :(

Did not work