for mpg1, mpeg4, divx.mp4 etc:
give Mpeg Streamclip a try to convert; probably, you need additionally install perian.org to teach QT additional codecs.
for mp2 conversion you have to purchase additionally the mp2-playback-component from apple.com/quicktime
keep in mind: iM is meant for camcorder imports, no 'edit all moving images'-tool
Try this it worked for me with movies from my camera that were in iphoto
1. Open your movie in Quicktime
2. Go to File and choose Export
3. From here you can name your movie. Name a folder you wish to put it in
4. Click Export
5. Go to imovie choose file and import then click movie
6. Locate the folder containing your movies from the menu and click import it will then load into imovie for you to use in a project.
No need to buy or instal converters
I am having the same problem. I have about an hour of mp4 video from a GopPro camera, and want to make a movie as shown in the iMovie demo. When I tried to put them in iMovie, they showed up as clips very briefly, and then the word "ERROR" appeared under each one, and they disapppeared. Now, I I try again, I get a "no matching video" message.
I can watch them in QuickTIme, so I know the videos are OK. I tried what was suggested in the November 28 response, and when the video was exported from QuickTime, it was converted into a .mov ifle from a .mp4 file. It also took almost 10 minutes to export a 2 1/2 minute file, so this is not really practical for about an hour of .mp4 files. In any event, it looked like it was going to work, but when I selected the new file to import into iMovie, I got a "no matching video" message in the event library screen, and nothing else happened.
Please help. One of the main reasons I got the camera was so I could make a movie of my dive trip. Thanks.