Apple has ended all support for QuickTime. No loss as QuickTime was always a bloated, slow piece of shit that you should have gotten rid of years ago. So, for those of you that still have QuickTime, uninstall it now and replace it with K-Lite Codec Pack:
http://codecguide.com/download_kl.htm

And for good measure, add VLC Media Player:
http://www.videolan.org/vlc

Uninstall QuickTime
Install VLC Media Player
Install K-Lite Codec Pack
In the settings for K-Lite, select VLC Media Player as the Default Player for everything

With both K-Lite Codec Pack and VLC Media Player, you will be able to play everything.

Press Release: Apple Ends Support for QuickTime for Windows – Contains Vulnerabilities that Remain a Risk

Source: https://www.us-cert.gov/ncas/alerts/TA16-105A

Systems Affected
Microsoft Windows with Apple QuickTime installed

Overview
According to Trend Micro, Apple will no longer be providing security updates for QuickTime for Windows, leaving this software vulnerable to exploitation.

Description
All software products have a lifecycle. Apple will no longer be providing security updates for QuickTime for Windows.
The Zero Day Initiative has issued advisories for two vulnerabilities found in QuickTime for Windows.

Impact
Computer systems running unsupported software are exposed to elevated cybersecurity dangers, such as increased risks of malicious attacks or electronic data loss. Exploitation of QuickTime for Windows vulnerabilities could allow remote attackers to take control of affected systems.

Solution
Computers running QuickTime for Windows will continue to work after support ends. However, using unsupported software may increase the risks from viruses and other security threats. Potential negative consequences include loss of confidentiality, integrity, or availability of data, as well as damage to system resources or business assets. The only mitigation available is to uninstall QuickTime for Windows.