I bought a Roku stick months ago. I tested it out on downloaded videos. It worked great. Now I tried it again and it doesn't work. Using the Roku app on my Android tablet, the video shows on the TV, not a smart TV, but doesn't play using the app. It just sits there with a circle in the middle with no movement of the circle.
Roku devices only play a limited number of video and audio codecs. They also only support a handful of containers (the three letters/numbers at the end of the file). Usually Roku can play MP4 files without an issue. They also support the MKV, MOV and TS container, but the codecs within those containers might not be playable. You would need to provide more detail about your video to figure out why it won't play. There are free programs like MediaInfo that can provide that information.
