what questions did you have after googling?
>>58935453
Install Archlinux
Then:
sudo pacman -Sy ffmpeg
Then:
ffmpeg -i /path/to/webm ~/filename.webm
According to ffmpeg documentation, for webm,you get better results in terms of quality and control of target file size using 2 pass recording.
>>58935497
>ffmpeg -i /path/to/webm ~/filename.webm
>Typical Archfag mistyping commands and then breaking X
AVI -> WEBM, brainiac.
>>58935596
My bad.
ffmpeg -i /path/to/avi ~/filename.webm