Auto HD|LQ for YouTube is a lightweight Firefox extension designed to enhance your YouTube viewing experience by controlling video playback quality. Users can easily set preferences for either High Definition (HD) for optimal clarity or Lowest Quality (LQ) to conserve bandwidth, making it suitable for various internet speeds. The extension supports both HTML5 and Flash players, ensuring compatibility with a wide range of videos on the platform.

One of the key features is the ability to switch quality settings directly from a convenient toolbar popup, allowing users to make adjustments on-the-fly. Additionally, there is an auto mode that lets YouTube determine the best quality based on the current connection speed. This functionality makes Auto HD|LQ for YouTube a practical tool for users looking to customize their streaming quality without hassle.