Per the list:
I'm running Opencast 4.0.0 (build 77e712a) in a four server setup (admin, NFS, presentation, worker) and have recently setup Piwik integration to allow statistics collection. This works well but every time you load a video with the Engage player (either embedded or not embedded) a little pop-up appears saying 'Usage data will be collected with Piwik. You can use the Do-Not-Track settings of your browser to prevent this'. Initially I thought this was a setting in Piwik and asked the question on the Matomo forums but apparently Piwik/Matomo doesn't generate any messages like this; it would be generated by the integration used (i.e. Opencast). I've had a look through the Opencast administration guide and can't find anything mentioning this pop-up. Assuming Opencast is generating the notification does anyone know how to disable it?
tl;dr: Make the notification regarding Piwik tracking optional at the admin level.