RE Quicktime
The reason you are having issues with this video is its aspect ration is wrong its not a native video size in anyway at all.
You have to reExport with correct settings.
1. Open with QTPro
2. Choose the Quicktime movie export option
3. Under the "Use" dropdown menu click on "Default Settings". This just gets things back to original export settings.
4. Click the "Options" button
5. If there is sound to your video you don't need to do anything here, just make sure the box is checked. Now click on the "Size" button and choose "NTSC 720x480 16:9". Next click the "Settings" button and change the compression type to "Apple ProRes 422" also check to make sure Frame Rate is 29.97.
Now you can drop the video in the FCP timeline and auto conform your sequence to the video and everything should be fine.
Always make sure your video is similar to what I have described above and adjust settings whether its SD or HD video. Unless you have imported directly from a camera yourself, always check your video settings to make sure they correct for editing.
I will open the video in QTPro and open up the "Info" window and check the FPS, aspect ratio and video codec. If its an h.264 or mpeg, basically anything other then an uncompressed codec that FCP understands then reExport so its right.