I am using Internet Downloader Manager from last 4 years and since then I am very much love with this. This is an amazing software which helps you download anything so easily.
Every download is just one click away. It is most helpful on youtube and few other online video or audio buffering websites where it can easily fetch the data and hello you download video and audio directly to your system.
You can also select the video quality on YouTube in which you want to download the video. downloading speed is amazing. I get awesome downloading speeds, much higher than stock downloader.
You have to purchase the licence and once you do you can get life time access to the software.
I must recommend this to everyone as this is amazing.