You can quickly convert files using ffmpeg, eg with a command saved in the .bat format in a folder with files:
Code:
for %%I in ("*.flv") do ffmpeg -i "%%~I" -y -hide_banner -loglevel panic -movflags +faststart -c:v copy -c:a aac -b:a 64k %%~nI..mp4
You can try many free applications that download in mp4, avi etc., e.g. this one:
https://xstreamloader.techweb.at/en/