I uninstalled the beta version during my testing. I reinstalled it, and I see that I was misreading the "about" page. The beta version is still 32-bits. Opera 12.15 does have both 32-bit and 64-bit versions, so I just assumed that was true for the current development branch as well. I have more browsers and virtual machines for testing than I can remember - sorry for the confusion.
My other post that was closed was a near duplicate of this one (I wasn't sure of the correct place to post this issue). The only difference is that I had additionally tested against the stable version and @font-face works for the stable version.