If you are still running OS X 10.6.8 Snow Leopard, the older version Final Cut Express 4 can import and edit these files.
I use this on my newer Intel iMac with OS X 10.6.8 running Rosetta.
Amazon still has these versions for sale here.
What year, screen size, CPU speed of your iMac?
To run even this version of Final Cut, you may need to increase your amount of RAM.
You, probably, can install more than 1.5 GBs of RAM.
If you are running OS X 10.6.8. 1.5 GBs of RAM is not even enough to run OS X Snow Leopard well, much less video editing software.
Correct and reliable Mac RAM can be purchased from online Mac RAM sources Crucial memory or OWC (macsales.com).
Thanks a lot for your quick reply!
These are some key machine specs:
Purchased in 2007
Intel Core 2 Duo
1.5 GB RAM
4 MB L2 Cache
667 MHz bus speed
128 MB VRAM
I'll look up Final Cut Express at Amazon, and check out the specs. Thanks a lot for the pointers! This really helpful.