This was really driving me nuts: It's important that the file extension is ".mp4".If you upload a video with ".m4v" extension you'll not see a preview window and the video is opened in an external player.
Wondering why videos won't play on your iPhone? Chances are that your device doesn't support the file format of the video you want to watch. Your iPhone works only with .m4v, .mp4, and .mov file formats for videos. But if you've just downloaded a movie from the web, it's likely saved in either .avi or .mkv. The built-in apps like Photos and Files just won't play such a video.
Codec is actually the abbreviation of coder-decoder. The name actually says it all: it's a method for encoding and decoding data, specifically compressed data. As you might have guessed by now, like.mp4, which is a popular video format for Android, there are video codecs for Android and audio codecs for Android. Usually, the job of a codec is to compress a set of data (video or audio) for storage and later decompress it for playback or viewing.
Usually, a container is also referred to as a file format. It takes care of packaging, transport, and presentation (while the codec prepares the file for these actions). Containers take care of synchronizing the audio and video. A container is part of the file that determines the file type. In simple terms - if you have a nextpit.mp4 file, MP4 is the container. 041b061a72