Hello ericfromnorth vancouver,
Thanks for using Apple Support Communities. It's our understanding that your videos appear as a still image when importing from Photos to an iMovie project. We're happy to help.
It is expected behavior for videos to appear as a still image for 3 to 6 seconds after dragging the video directly from Photos. We recommend that you drag the video from Photos to your Desktop first, then drag the video from the Desktop to the iMovie project. Please review the resource below to make sure you've followed all appropriate steps:
Add photos and videos to your iMovie project
Let us know the results. Please include any troubleshooting steps that you may have tried.
Have a nice day!