Save time user watched video and keep watching

Well, I finished a PHP course, I'm not an expert and I'm creating a course system. I need when the user starts watching the lesson, the system saves the video runtime every 3 seconds. And save this so that the next time he enters the site, he can continue where he left off! I thought of doing with localStorage, cookies and others. But I need that from where the user access, he can continue watching. I thought about sending the time to the Database. I just do not know which structure and function to do this. Could you help me?