I don’t know for sure - but I’d bet it is WAY easier to grab those parameters (email/ip) from your browser session and overlay them over the video with css or JavaScript than it is to actually encode the video for every user with those details in place in realtime. Since any user could access via any ipaddress, it would need to recode each video every time you click to watch. Which is possible but seems wild to do. Much more likely it is an overlay - especially if you don’t see it upon download. Someone smarter should weigh in