Cannot import video into iMovie

Just to echo what another user said in a comment, if installing Perian and DivX didn't work you might try converting the video. Just download Handbrake and convert your video to H.264, then try importing that into iMovie.

I think your problem has something to do with not having the right Codecs (the bit of software that translates one type of video to another type). @Martin is right - if you can convert your video yourself you'll solve your problem, but it would be even better if you can teach iMovie to convert it for you.

Try installing both Perian and DivX (I'm too new to post two hyperlinks, just Google DivX Mac - it's the top link) and then restart your computer - this will install extra codecs to allow you to covert between the different types of video.

Using the VLC player, use the Media Information or Codec Information commands in the Tools menu. This will tell you the original codec.

Chances are that the codec is not one of the ones in Quicktime, or Perian. I am guessing iMovie opens the file, goes through the codec list, can't find it, and fails.

If the movie plays on a Windows machine, iTunes for Windows might convert it if you select it in the iTunes library, and choose 'Create iPad or AppleTV Version' from iTune's Advanced menu.