How to stream video stored in S3 on html?

I have few video files uploaded on Amazon S3. I need to play those on an HTML page programatically one after one.

Few questions - 1. Why is the video not stored with any extension on S3? 2. When opening the AWS S3 link it directly asks to download it and save in some format. Can't we achieve it without downloading it? 3. From reading few articles I understand streaming is possible with using cloudFront and JW player. So can't we use HTML5 tag then?

Few of my questions are very amateur, so you can ignore them. But do guide me to eliminate doubts and if you can tell me the current solution BROADLY. I will manage the details. TIA