Quick Translate for YouTube Captions is a Firefox add-on designed to enhance the viewing experience by allowing users to easily translate captions and subtitles on YouTube videos. With a simple button added to the YouTube interface, users can translate captions with just one click, making it convenient for viewers who prefer content in different languages. The add-on supports translation services from both Google and DeepL, and users can customize their preferred translation service according to their needs.

In addition to translation, Quick Translate also provides a feature to look up individual words used in captions through its menu. This functionality is particularly useful for language learners or anyone wanting to expand their vocabulary. Users can customize online dictionary settings and have the option to select and copy subtitle text when the 'Look up words' feature is disabled. This add-on is also available for Chrome users with a few additional installation steps.