I suspect your problem is the older OS and iPhoto -- but I do not know -- hopefully some of the more expert users (Terrence, Old Toad, Larry) will join in and make suggestions. Many of them are in Europe -- wait until tomorrow before you do anything so they can perhaps offer suggestions. (But I still can't get my avchd in iPhoto 9.4.3, either...)
Your 8.1.2 probably isn't going to do it, based upon the KB Old Toad has found ... but, try changing to MP4 format first, as a test, and see if it works....that, at least, would allow you to further postpone the decision to upgrade software (although, I always recommend updates -- a few days after they are issued -- and OS upgrades (like to OS 10.8) a few weeks after issued).
Great to hear from you again and thanks for linking to the KB -- I am curious, however, why my MBProRet has decided, seemingly overnight, not to import direct thru iPhoto when it used to....I don't recall any iPhoto updates in the past few days....I suppose the answer is simply "some things are not to be known," right? Hopefully it will straighten out.