You are correct, thank you for clarifying. You guys need to update the documentation. It currently says:
BitNami virtual appliances ship an OVF file which makes it easy to import the machine in VirtualBox 3 or previous versions. If you are using Virtual Box 4 or later, you would like to import the Virtual Appliance manually.
3. Choose "existing hard disk" and select the BitNami "vmdk" file. Be sure that you select the main one (without s00X in the file name, not any of the other vmdk files: s001.vmdk, s002.vmdk, etc).
It sounds like manual importing of the VMDK no longer works in VirtualBox 4, and the OVF must be used? These are the instructions I followed which gave me the error.