Theres a good chance that if you click your download button using an Android device, that nothing will happen. Its not that the download button is broken or faulty (we use Google Cloud)... it's simply that Phones and tablets aren't great for downloading large video files from the internet.
Its easy to take a HD video clip with the camera on your phone and everyone knows how to send/receive a video via WhatsApp, Facebook, iMessage etc..... but straight up downloading any large video file from the Internet to your phone/camera roll, can't be done directly.
For android users, you will most likely have to download via Google Drive or a similar alternative.
For iOS users
Chrome seems to be the least useful for downloading large files, we would politely suggest using Safari if you are on iOS.
The video won't download directly to your phone/camera roll (as they are so large), instead the video file will basically go straight to your iCloud Drive where it can be accessed via the "files" app. However, If you do not have the free iCloud space available, the download will likely never begin.
We recommend a full browser (Chrome/Firefox/Safari etc) on a desktop PC or Mac for an easy download