Just Install your Add-ons. Refresh the youtube link, click on Download icon (Red button, click choose HD quality, the addon asking for saving location, choose Desktop, and looking into downloaded icon on taskbar, but its say 0 byte. What happent? )
When I click to download, it only gives me a file with the name of the video but without any content. For example, I click to download a video of cats, it is finished downloading, I check it and it says 0kb, I open it and it says that the format that was damaged or was changed. In a few words, download an empty file.
In the last day, nothing will download. Nothing means every single video I try to download will not download. I get the save screen that shows the title the video to be saved and then the little arrow that shows download completed flashes in about a second or two and I have a file of 0 bytes I refreshed firefox, but no help