There are a lot of counter-intuitive things that come up in technology. It's my guess that the reason they loop the video inside the video file is because some mobile browsers don't "cache" or fully download the video file. The implication of that would be that the video file is downloaded twice to play it twice. However, If the video loops existing frames in the file, then the compression can take advantage of things already in the file, leading to a slightly bigger file, but less bytes downloaded overall to play multiple times. Multiply it by the total number of users, and you're looking at a potential savings of quite a lot of money, at the expense of the odd user here and there that only views the content once and then stops the video exactly before it loops.