you are generally not using videos in Cubase/Nuendo.

A new Quicktime independent video engine has been introduced with Cubase 9.0.30 (all versions: Pro, Artist, Elements, AI, LE) and Nuendo 8.

you are using a current Cubase/Nuendo version.

You can safely uninstall QuickTime for Windows, if. It depends on the Cubase/Nuendo version and your requirements if uninstalling QuickTime for Windows affects your installation of Cubase/Nuendo. Impact of uninstalling QuickTime on Cubase/Nuendo

Therefore, Apple recommends to uninstall QuickTime via Control Panel > Programs and Features. Regardless of Cubase/Nuendo, QuickTime constitutes a security risk on Windows systems. In any case, the risk increases constantly due to the missing security patches.

It also seems to require user actions like clicking internet links or opening malicious files. According to reports, an attack through the security gaps in QuickTime for Windows is possible, but not highly likely. The actual risk of security gaps in QuickTime for Windows is unknown. Since the video engine of older Cubase/Nuendo versions requires QuickTime, this concerns many Steinberg software users, too. Apple also confirmed security gaps in QuickTime for Windows which have been discovered previously. There will be no further updates or security patches for QuickTime on Windows. In April 2016, Apple discontinued support for the Windows version of QuickTime.

Information on the QuickTime-independent video support in more up to date Cubase and Nuendo versions can be found here. Please note that this article refers to program versions prior to Cubase 9.0.30 (all derivates: Pro, Artist, Elements, AI, LE) and Nuendo 8.

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