Good news, I found a solution to deal for once and all with the problem with iphoto refusing to import my mp4 movies, while in OSX 10.6 (I'm not upgrading to Lion).
And the solution is plain simple: ABANDON THE PROGRAM ALTOGETHER!!
I am finally free of iphoto and all its limitations and downspiral from a couple of versions back. This program offers little in terms of functionality and the cost of using it is far too great. I truly dislike how a program that used to be somewhat useful is now useless. For instance, in the past I was able to assign a them or a title to my imports and that name would be on the folder inside the iphoto Library (access it by right clicking, view package contents). Well, since version 11 one can no longer do this instead you're limited to plain numbers assigned by iphoto that you cannot modify. Not of much use when searching my hard drive for pics of my kids on his birthday.
So I am now finally free of the prison that is iphotos. Now I import my pics onto folders that I am free to name inside of my Pictures folder. So means next time I'm trying to quickly locate those holidays pics, I just type that in the search and there it is. No need to go into iphotos and fight with that useless app. Oh and furthermore: i have no problems importing my mp4 movies from my Samsung and other cameras. Wow. Take that, iphoton.
Another benefit of getting rid of anything related to iphoto is that i reclaimed over 5 gigs from my hd.
For anyone looking to break free from this awful app:
1- go to your Pictures folder, locate the iphoto Library.
2- right click it and choose view package contents.
3- go to Masters (or in previous versions, Originals) folder and all your pics are there.
4- move these pics from inside the iphotos Library out onto a folder of your choosing, A good place is in the Pictures folder itself.
5- once you move all your original pics feel free to delete the iphotos library and it will yield a lot of free disc space. Or leave it alone if you plan to go back to it one day, should the program actually improve someday.
Then when you want to import your new photos, just hook up your camera and it will display in your desktop (like a mounted disc). Simply copy the pics and those mp4 files that iphotos can't read to a folder of your choosing. Simple drag and drop.
I shall never again use iphotos. What a disappointment this episode has been.