Is Video Expansion Controller safe?

Adds playback speed, seek, and mouse-wheel controls to supported video websites.

This extension adds video control buttons and mouse actions for sites such as YouTube, Nico Nico Douga, Amazon Prime Video Japan, Twitch, and TVer. It can add speed changes, seek buttons, click-and-hold fast-forwarding, and mouse-wheel actions for seeking or changing playback speed; some sites also support click-to-maximize and resume playback. The description notes that not all features work on every supported site.