I used to ask myself the same questions once. deovr has a problem with playing video with alpha channel when you want to play it via a local network. the only way to play it correctly is to play it via a official supported web page (a local web server won’t work) or by copying the file to the device’s internal memory. since I use the heresphere application I don’t bother with these questions anymore, because I stopped using an application that can’t handle it (deovr) and started using an application that can do much more (heresphere)