Conversion failed. A required codec could not be found or failed to install

user@homesrv:~/docker$ sudo docker exec -it plex bash
 /# ls
Media  config  etc             init              lib32    libx32  opt              proc  sbin  tmp        var
bin    data    healthcheck.sh  installBinary.sh  lib64    media   plex-common.sh   root  srv   transcode  version.txt
boot   dev     home            lib               libexec  mnt     plex_service.sh  run   sys   usr
 /# nslookup downloads.plex.tv
bash: nslookup: command not found
 /# curl downloads.plex.tv
<html>
  <head>
    <title>Plex Redirect</title>
      <META http-equiv="refresh" content="0;URL=https://plex.tv/downloads">
  </head>
  <body bgcolor="#323232" link="yellow" vlink="yellow">
    <p>&nbsp;</p>
    <center><font size="5" color="white">The page you're looking for was not found.<br>
      You will be redirected automatically in 5 seconds.<p>
      <a href="https://www.plex.tv/downloads">https://plex.tv/downloads</a></font>
    </center>
  </body>
</html>
 /# wget https://downloads.plex.tv/codecs/fa235d6-3858/linux-x86_64-standard/libh264_decoder.so
bash: wget: command not found
 /# curl https://downloads.plex.tv/codecs/fa235d6-3858/linux-x86_64-standard/libh264_decoder.so
Warning: Binary output can mess up your terminal. Use "--output -" to tell
Warning: curl to output it to your terminal anyway, or consider "--output
Warning: <FILE>" to save to a file.
 /# curl https://downloads.plex.tv/codecs/fa235d6-3858/linux-x86_64-standard/libh264_decoder.so --output
curl: option --output: requires parameter
curl: try 'curl --help' or 'curl --manual' for more information
 /# curl https://downloads.plex.tv/codecs/fa235d6-3858/linux-x86_64-standard/libh264_decoder.so --output libh264_decoder.so
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 1601k  100 1601k    0     0  2993k      0 --:--:-- --:--:-- --:--:-- 2993k
 /# ls
Media   data            home              lib32               libx32  plex-common.sh   run   tmp        version.txt
bin     dev             init              lib64               media   plex_service.sh  sbin  transcode
boot    etc             installBinary.sh  libexec             mnt     proc             srv   usr
config  healthcheck.sh  lib               libh264_decoder.so  opt     root             sys   var
 /#

I checked it from the inside of container…I really confused