If you're getting an error about "Could not access the downloads folder", go to the extension's "Manage Extension", click on the "Permissions" tab and enable the "Download files ..." permission.

works fine for normal things, but if you want something high quality and high fps it fails, the video records are not so smooth if you record any browser animation or any video playing.

Works fine, but video quality is pretty bad even on "high" setting.

It doesn't allow to record a tab in Firefox. It only records the whole window, though I selected Tab, then clicked Start. Otherwise video is viewable and I like how it is easy to use.