You might be able do it with a delayed loop or something
Create clip list file
Code:
(for %%i in (*.flv) do @echo file '%%i') > mylist.txt
Join all clips together once the stream has ended
Code:
ffmpeg -f concat -i mylist.txt -c copy output.flv
The thing is though even when you join files there's an offset between the two files because the second clip contains around 1-2 seconds from previous clip as it's starting point so you need to trim them otherwise you'll get jumps.