could you elaborate on what night mode, resource sniffer and changing browser id string is or what it does
Night mode turns the background into black and the text to white (or whatever color you want, you can set it in Options).
Resource sniffer: similar to "network sniffer: -- you can download and save almost everything that is being displayed or played by the browser, including .swf files, youtube videos (and videos of other sites), audio files etc. As a result, you do not need programs such as youtube downloader etc.
Browser id is the how a website sees what OS and Browser you are using. For example, if you would like to see the mobile-phone-version of a webpage, you can just change the browser id to Android 2.5 or iPhone, etc.