Video files can be converted using GUI tools such as Handbrake, Arista, WinFF but if you don’t mind the command line – or if you want to automate video file conversion then the following examples might help:
Convert to FLV
ffmpeg -i video.avi video.flvffmpeg -i video.avi -ar 22050 -ab 32 -f flv -s 320×240 video.flv
-i input file name
-ar audio sampling rate in Hz
-ab audio bit rate in kbit/s
-f output format
-s output dimension