why won't my BDMV video file upload into iMovie ?

'BDMV' is just a part of a AVCHD-structure ...

Do you import from a camera/SDcard?

Hello, I found this instruction from anther post talking about similar topic. This is what works for me. Hope it works for you too:

Launch iMovie, and then Except physically connecting the camera to USB, also connect it via a "Connect to USB" command on the camera; When connected, iPhoto will startup as well. Just ignore;

iMovie will (after some time) show an import screen, giving you the option to archive all video content from your camera and/or import clips (selectively). If it doesn't choose "Import from camera..." under the File menu option;

If the import screen is not shown or your camera is not found, chances are iMovie does not see your camera. This could be because you did not logically connect it on the camera itself. If you turn on your camera and then physically connect it to USB, do you see a pop-up on you camera screen ? Is there a menu option to activate a USB connection?

Hope this works for you too.