An EXO file is a video chunk file, downloaded by Android version of YouTube in the EXO format. When a user wants to download a video for offline playback, the video is divided into small chunks and each chunk is downloaded and saved to user’s device as an EXO file. These multiple EXO files are joined together for offline playback by YouTube app.
EXO File Format
EXO files are saved in YouTube’s proprietary file format. They are saved as compressed encrypted files and can only be opened with the YouTube Android application. All the multiple downloaded chunks are assembled and decrypted by the app to be played offline. Being encrypted, EXO files can not be converted to any other file formats such as MP4.