My only criticism of this is there is little info or description on why games developed on Java by Gameloft are fire. Gameplay, mechanics, grahics? But very informative nonetheless.
Your explanation about Java at 1:45 to 2:26 is wrong. You mix Java and JavaScript together, but both are not much related. They are coming from different developers and have different goals and philosophy in mind. To keep the explanation simple, they execute the code differently and the style of coding is different if you look closer. The Java in JavaScript is only there because the dev abused the good reputation of Java. Java is NOT powering your websites and web application as you described it. JavaScript is doing that. But yes, Java can be used for the backend of websites/web apps and runs on a lot of machines, such as old mobile phones to run the games. You may remember those covers or ads in DVD boxes or installer describing how it runs on millions of machines.
I think that is what he meant. Given the context - Java to a website would be a backend, like spring boot. Java to a mobile application would do the same thing similarly, using react native as front end. In a video game, would scripts (written in Java or C#) be considered backend, or would it be similar to JavaScript in that it dynamically modifies the UI in real time?