eco1 is a Chrome add-on that allows users to switch to economy video quality on Nico Nico Douga by adding "?eco=1" to the end of the video page URL. This extension provides a convenient way to force the video quality to economy mode.

After installing eco1, users can easily toggle the functionality on and off by clicking on the icon that appears. This makes it simple to switch between different video quality options based on personal preferences or internet connection speed.

With eco1, users can enjoy a more optimized viewing experience on Nico Nico Douga, especially when dealing with limited bandwidth or slower internet connections. This add-on is a useful tool for those who want to conserve data usage or improve video playback on the platform.

Please note that eco1 is available for free and can be found in the Browsers category under Add-ons & Tools. It is developed by te and is specifically designed for Chrome users.