When you select "Contacts" from the left side navigation bar, iBackup Viewer will load the backed up contacts, and it will look like:
Change the group from group drop down to show contacts within the group, you can search to find contacts match to given keywords.
iBackup Viewer shows contacts in ascending order by default, and sorts by full names.
The sorting result depends on the system locale settings.
You can export all contacts to system address book, actually the Contacts.app (AddressBook.app prior to Lion)
This option behaviors almost same as "Save All to Contacts", but it will try to put the contacts in to groups and create the groups if they are not existing.
If you would like to save only the chosen contact to system address book, select this option.
If you want to share backed up contacts for some usage, the best way is using vCards, which is known as *.vcf files.
Write the selected contact to vCard file.
Write out all contacts as separate .vcf files.