DualCaptions Multi Subtitle is a free mobile app designed for iPhone users, developed by Kenji Otsuki. This app falls under the Education & Reference category and offers a unique feature allowing users to watch YouTube videos with two sets of captions simultaneously. By adding an extra caption language, users can enhance their understanding of video content, learn new languages, or simply enjoy videos with an additional layer of information.

The app's user-friendly interface simplifies the process of adding a second language caption to videos, making it accessible to all users. By selecting a second language from the list and tapping the 'YouTube' button, users can seamlessly enjoy videos with dual captions, enriching their viewing experience.