This patch allows to change default filename extension for subtitle files from ".srt" to i.e. ".txt".
Use case: I.e. my wife uses the popular (in our country) program to download subtitles "Napiprojekt for Windows". She doesn't know anything about converting subtitle files. She just want to "click" and get the subtitles working. The subtitles are fetched as *.txt files. I would like to change the default filename extension for caption files from *.srt to *.txt.