I tried again. This time Success. See below.
I also found my old (shudder) Windows 10 SSD. Fired it up and tried to run the .avi movie. Result? Same error code. Now I reckon that the movie is corrupt. I was sure that it worked first time I tried it but then again... Will contact my nephew to see if this happened to him also. Whew. Thanks for your help Condo.
johnj@johnj-Z97-D3H:~$ sudo apt update && sudo apt install mint-meta-codecs
[sudo] password for johnj:
Get:1 file:/usr/lib/expressvpn/repo_mirror.list Mirrorlist [117 B]
Hit:3 http://mirror.aarnet.edu.au/pub/ubuntu/archive jammy InRelease
Hit:4 http://mirror.aarnet.edu.au/pub/ubuntu/archive jammy-updates InRelease
Hit:5 http://mirror.aarnet.edu.au/pub/ubuntu/archive jammy-backports InRelease
Ign:6 https://mirror.aarnet.edu.au/pub/linuxmint-packages virginia InRelease
Hit:7 https://mirror.aarnet.edu.au/pub/linuxmint-packages virginia Release
Get:2 https://repo.expressvpn.com/public/deb/debian any-version InRelease [4,580 B]
Hit:9 http://security.ubuntu.com/ubuntu jammy-security InRelease
Get:10 http://repository.spotify.com stable InRelease [3,316 B]
Err:10 http://repository.spotify.com stable InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 6224F9941A8AA6D1
Reading package lists... Done
W: GPG error: http://repository.spotify.com stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 6224F9941A8AA6D1
E: The repository 'http://repository.spotify.com stable InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
johnj@johnj-Z97-D3H:~$ sudo apt upgrade
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Calculating upgrade... Done
The following packages were automatically installed and are no longer required:
linux-headers-5.15.0-106 linux-headers-5.15.0-106-generic
linux-headers-5.15.0-107 linux-headers-5.15.0-107-generic
linux-image-5.15.0-106-generic linux-image-5.15.0-107-generic
linux-modules-5.15.0-106-generic linux-modules-5.15.0-107-generic
linux-modules-extra-5.15.0-106-generic
linux-modules-extra-5.15.0-107-generic nvidia-firmware-535-535.171.04
Use 'sudo apt autoremove' to remove them.
#
# OpenSSH CVE-2024-6387 has been fixed for 22.04 LTS, 23.10 and 24.04 LTS.
# RegreSSHion: Possible RCE Due To A Race Condition In Signal Handling.
# For more details see: https://ubuntu.com/security/notices/USN-6859-1.
#
The following packages have been kept back:
ubuntu-advantage-tools ubuntu-pro-client ubuntu-pro-client-l10n
0 to upgrade, 0 to newly install, 0 to remove and 3 not to upgrade.
johnj@johnj-Z97-D3H:~$
