Some users have reported that the Canvas window will show video that is slightly blurred or softened when the video is playing back.
This can occur on configurations running Final Cut Pro HD (4.5) under Mac OS X 10.3.6 or Mac OS X 10.3.5 with NVIDIA graphics cards. This issue does not affect the final output, and should only appear in the Canvas when the video is in motion; when the playhead is still, the Canvas should display normally.
This issue is addressed in the Mac OS X 10.3.7 Update. Please update to Mac OS X 10.3.7.