I keep getting this error message upon every sudo apt-get update command, and plenty f other times while downloading and installing new software and packages... I was wondering if someone could help.
E: GPG error: http://donwload.vidoelan.org InRelease: Clearsigned file isn't valid, got 'NODATA' (does the network require authentication?)
That URL you have there is bad (perhaps even malicious ?) - note that you have
http://donwload.vidoelan.org/
^^ ^^
Which is incorrect - it should be https://download.videolan.org/, which does work, whereas the one you have just gives an empty page.
You need to remove this repository. To do so, open the "Software sources" utility (find it in the dash), go to the "Other software tab", and, if there's an entry for Videolan (or Vidoelan..), uncheck it.
