If this button does nothing for you, try looking at the browser menu for the 'Add to Home Screen' option. Give it a try, it works best on Android and Windows devices, all it takes is you have to have Chrome installed on your device.
This is a very good application, it will never need any updates, because it will update automatically when our website is updated. It has Youtube search and can convert videos to mp4 as well as mp3. It is full of features as is the website.
It is lightweight and takes up very little space on your device. Download.Tube now has a free web-based application which can be installed very quickly and easily.