The Mp4 format video is now created by default when you upload a video. Now, in addition to a streaming video playback, you can provide a static mp4 video.
In addition, adding the parameter dl=1 to the video url will force the browser to download the video. Now you can show the video, and have a “click to download” that downloads the video (and does not open the video to play in another window:
The link above is: https://cdn.api.video/vod/vi1FBKkaYe5Y2L9wNbGDYztl/mp4/720/source.mp4?dl=1