The most common reason a user will get an "Error Code 428" is they have multiple simultaneous, active sessions (such as leaving yourself logged in on a mobile device, and on a desktop browser, at the same time). This creates a conflict in site and video permissions, and can sometimes result in your seeing that error message when trying to play a video. Doublecheck that you didn't just close a browser on one device before initiating a download on a new one, that you don't have simultaneous download attempts in multiple tabs or browsers on the same device, and so on.
Additionally, ff you've been logged in on a single session for more than 10 hours, you may need to log out then log back in to re-enable streaming. Because of some devices' and browsers' settings, it might be best to click the LOG OFF button, then re-logging in, as opposed to simply closing a browser window.