Question: how idm works in firefox?
Answer: Please use "Tools->Add-ons" FireFox main menu item. "Add-ons Manager" window should open. Click on "Extensions" tab (arrow 1 on the image) and find "IDM integration" (Internet Download Manager integration add-on for Mozilla). If it is disabled, you will need to press "Enable" (arrow 2 on the image) and restart FireFox.