Video not playing on Macbook

Let's start from the beginning:

Major Issues:

Anything that appears on this list needs immediate attention.

Security updates disabled - Security updates are disabled. This computer is at risk of malware infection.

Apple security disabled - Apple security software is disabled. This computer is at risk of malware infection.

You are putting yourself at risk by disabling the built-in system security

Minor Issues:

These issues do not need immediate attention but they may indicate future problems or opportunities for improvement.

More than one antivirus app - This computer has multiple antivirus apps installed.

No Time Machine backup - Time Machine backup not found.

And then you installing more than one third party "antivirus"... the correct number is zero.

See this invaluable post about having proper security in your mac:

Effective defenses against malware and other threats

I will look into the rest of the report and let you know.

I have a feeling that cmm is in there...

Did you restart your mac?

Try restarting in Safe Mode and test. Does video play?

If the problem persists even after restarting then most likely something was installed is wreaking havoc.

Please run Etrecheck and post its full report here.

Use the “additional text” button and paste the report into the text box.

And I was right :-(

Antivirus software: F-Secure and CleanMyMac

Uninstall these two, according to their developers' instructions.

CleanMyMac is certified poison.

Even after uninstalling, we cannot be sure that things return to normal, as it may already have caused damage.

One other thing: your disk space is getting a little low: only about 50GB, that's 10% of your drive.

Performance starts to degrade when free space is low. It may not yet be noticeable, but keep that in mind.

It is usually recommended to have at least 15-20% free space, especially on a system drive.