Working on an iMac with OSX 10.10.5, 16Gb Ram, ATI Radeon HD 4670.
Have made a couple slideshows with video but now Getting error message: "There was an error working with the video".
Had recent success with .MOV but these are .AVI from Olympus camera.
Have tried unchecking the cache size, permissions rebuild, other tips from common problems but it never changes issue.
Update - the .mov files no longer play back either now. I edited them and exported them a couple weeks ago. Can't make sense of this.