Doesn't work on Firefox?

Remember history

Check that Remember History is selected. This is currently required for the addon to work, but we're looking into a workaround.

This is in Firefox Settings -> Privacy & Security -> History Section .

Also accessible via about:preferences#privacy in the toolbar.

Go to extensions management , Video DownloadHelper, Permissions and data tab, check Access your data for all websites

If you use private windows, choose Allow in Run in Private Windows section of Details tab.