I have the same problem, which probably started after one of the latest upgrades of Aperture. All of a sudden I can not import any video files, either from the computer or from a memory card. Last video files I imported were last summer.
My settings are the same, I haven't changed anything and I am sure my Import Settings are correct. I am not excluding any file types, I haven't selected the RAW+jpgs pair or anything, the only things I have in my Import Settings are the Metadatas and the Effects selection, but I tried removing them too and it didn't work. I have also checked the file permissions and they are the same as those of the existing video files which I have in my Aperture library, I have tried to repair the library etc, nothing. I have also tried importing .mov, .m4v video files or files directly from my Canon S90. Nothing.
Any help will be greatly appreciated.
iMac 24-inch, Early 2009, running OS X 10.8.2 (12C60) and Aperture 3.4.3.
I haven't selected the RAW+jpgs pair or anything,
You need to select exactly "RAW+jpg" pairs, otherwise, Aperture will import only jpeg or raw, and a video file is neither of those. If that does not help, check your video codecs:
Check, if you have the codec 3ivxVideoCodec.component installed, see how to remove it, if necessary: Aperture 3: May be unresponsive or have slower performance with third-party video codec
Also, try if removing the Flip4Mac video components will help, if you have them installed.
I did all of the above, delete anything related to Flip, the 3ivxcodec, the Perian. Nothing works, Aperture just refuses to see a video file, either from a newly formatted card (formatted in the camera) or from a directory on my disk. And I have selected Both (Use RAW as original) in the Import Settings (none of the other settings change the behavior either).