Unluckily I don't have much time at the moment to work on versions for different OSes.
Yes, Songr uses the default system proxy. Even if you use Firefox as your browser, you have to set the Internet Explorer proxy because it is the system-wide proxy for every application (Control Panel, Internet Options, Connections, LAN Settings)
Songr downloads the web page with the search result for every search engine and quickly identifies the url of the mp3 file and other metadata using the html tags near the data.
Start Songr, click Search by lyrics, type a few words and press ENTER. Right click -> Preview to listen to a preview. If it is the right song, double click it to search for mp3 files.
Songr searches the words you typed in Bing plus adding "lyrics" to the query, reads the titles of the results, filters them using heuristic techniques and tries to restore the original case.
I'm not a native English speaker, please report them.
No, mp3 files are downloaded from web servers and are not shared with other people during or after the download.
They are hosted on many different web sites. Hover the mouse over a song to read its address.
In order to speed up downloads and minimize the number of HTTP connections, Songr uses an internal lightweight proxy. In this way, you can listen to a song and download it at the same time using just one HTTP connection. The proxy runs in a separate process (Songr.exe), that closes automatically after a few minutes of inactivity.