According to the Windows 7 Compatibility Center, the DCR-HC21 is not compatible with Windows 7 64-bit (as you stated). It is the responsibility of the device maker to create the drivers for the different operating systems they want their products to work with.

Windows 7 Compatibility Center
http://www.microsoft.com/windows/compatibility/windows-7/en-us/Search.aspx?type=Hardware&s=DCR-HC21

Sony eSupport DCR-HC21
http://esupport.sony.com/perl/model-documents.pl?mdl=DCRHC21

Going through Sony's support I did find this:

Sony eSupport DCR-HC21 Download Files
http://esupport.sony.com/US/perl/swu-list.pl?mdl=DCRHC21

The above page does list Windows 7 64-bit in the dropdown list; when selected it lists:

Driver & Compatibility Information for Windows Operating Systems
http://esupport.sony.com/US/perl/support-info.pl?template=&info_id=544

Using outdated or corrupt Sony MiniDV HandyCam DCR-HC21 drivers can cause system errors, crashes, and cause your computer or hardware to fail. Furthermore, installing the wrong Sony drivers can make these problems even worse.

  • This page contains information about installing the latest Sony MiniDV HandyCam DCR-HC21 driver downloads using the Sony Driver Update Tool. Sony MiniDV HandyCam DCR-HC21 drivers are tiny programs that enable your Camcorder hardware to communicate with your operating system software.
  • According to the Windows 7 Compatibility Center, the DCR-HC21 is not compatible with Windows 7 64-bit (as you stated). It is the responsibility of the device maker to create the drivers for the different operating systems they want their products to work with.

On this page, it states (in part):

Windows 7

Drivers:
The drivers needed to connect your Sony camcorder to a computer and transfer files are already included in the operating system.

Not Supported:
The USB streaming feature is not supported with the Windows 7 operating system.
The Windows 7 Starter edition is not supported.

You might want to visit the Sony Forums as I'm sure this situation has been discussed there:

Sony Forum
https://forum.sel.sony.com/?XID=M:showcase:esupport

Regards,


Drivers

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Manufacturer:Sony
Hardware Type:Camcorder
Model:MiniDV HandyCam
Series:DCR-HC21

Compatibility:Windows XP, Vista, 7, 8, 10
Downloads:82,571,945
Download Size:3.4 MB
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This page contains information about installing the latest Sony MiniDV HandyCam DCR-HC21 driver downloads using the Sony Driver Update Tool.

Sony MiniDV HandyCam DCR-HC21 drivers are tiny programs that enable your Camcorder hardware to communicate with your operating system software. Maintaining updated Sony MiniDV HandyCam DCR-HC21 software prevents crashes and maximizes hardware and system performance. Using outdated or corrupt Sony MiniDV HandyCam DCR-HC21 drivers can cause system errors, crashes, and cause your computer or hardware to fail. Furthermore, installing the wrong Sony drivers can make these problems even worse.

Recommendation: If you are inexperienced with updating Sony device drivers manually, we highly recommend downloading the Sony MiniDV HandyCam DCR-HC21 Driver Utility. This tool will download and update the correct Sony MiniDV HandyCam DCR-HC21 driver versions automatically, protecting you against installing the wrong MiniDV HandyCam DCR-HC21 drivers.

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