Q:

Converting .m3u playlists from Windows for Android media players using Notepad++

Winamp saves playlists that are saved in same folder as the music as relative paths for Windows, but copying and pasting into Android doesn't work unless I convert it to Linux relative paths. So    
#EXTM3U
#EXTINF:262,Corona - Rhythm Of The Night
Unsorted\Corona - Rhythm Of The Night.mp3
#EXTINF:324,The B-52's - Love Shack
The B-52's - Love Shack.mp3

needs conversion to
#EXTM3U
#EXTINF:262,Corona - Rhythm Of The Night
./Unsorted/Corona - Rhythm Of The Night.mp3
#EXTINF:324,The B-52's - Love Shack
./The B-52's - Love Shack.mp3

for VLC Player on Android to read the playlist properly.
Well, figuring out how to convert \ to / on Notepad++ without regular expressions enabled was easy enough, but I'm too new at regex to get a grip on how to even read the table of contents on its guides even though all I want to do after that is to add ./ to the start of every odd line after the first line.

A:

You may use
(?:.*\R){2}\K

and replace with ./.
Details

(?:.*\R){2} - two consecutive occurrences ({2}) of any 0+ chars other than line break chars, as many as possible (.*),
\K - match reset operator discarding all text matched so far from the match buffer.

The replacement is ./, i.e. it is inserted at the end of the match.

