After installing Windows 7 64 bits from scratch, I discovered that CamStudio do not have support for it, only for 32 bits versions, and that’s kind of a pain if you like this software but are unable to use it in a non-32bit system. Although the software is not compatible, there is an alternative to use it.
To use CamStudio in Windows 7 64 bits, you need to download the portable version provided by PortableApps.com. And the best part is that is also compatible with any 32 bit system, making it quite a useful program to carry with you in your USB Drive.
Link | CamStudio Portable