This issue appears in Chrome browser while running a published Storyline course in an LMS. A download button appears on the video control bar below the video. This would enable all students to download the videos to their local machine.
The fix is simple and just means adding some lines of CSS to the CSS file in the published Storyline file in the zipped package and re-zipping it. This does not affect the LMS as it just redefines the parameters on the WebKit controls in CSS for the video and audio to ensure any download options, have been disabled.
Instructions to update:
Locate the file: player.CSS in the zipped published package for example: [ModuleName]\mobile\player.css
Ensure you have unzipped it locally to apply the fix