IMovie 10.0 and re-dating movies - go missing

Question

Hi,
I have used iMovie in the past for kids school projects, but now I have begun working with about 17 years worth of home movies.
I burned them to DVD on a sony DVD player and moved them to the mac using Handbrake to create m4v files (some are mp4 as I guess I used different settings on Handbrake when I created the files)
Anyway, I imported them to iMovie and then began re-dating the clips (using the on camera date stamp as my guide LOL).  I did the whole set only to have iMovie Loose track of the video and tell me to re-import the files.
Like a fool I began doing the who process again and after re-dating about 6 files it showed the same error.
So, am I doing something wrong?   Can I change the record date with some external application and them import?
Thank you,
Mike
(PS I found that I cannot split clips which are m4v or mp4, but the new clips from my 1DX which are .mov files I can split - any suggestions on this?)

Answer 1

The exact same thing just happened to me.   In the prior version if imovie I had carefully dated all my old analog camcorder tapes that I imported.  Yesterday I opened imovie 9 and noticed for the first time that all my older videos were missing.  On further inspection I found they were no longer dated right.   Dated at the import date.  I changed a bunch of clips - I watched them and used the time stamp to re-date.  The adjust date feature only let me change the end date - the start date was written in (unchangeable) as the imported date.  I changed the end date to the proper date of the clips.   After doing a bunch I noticed that the clips are now showing as missing files.   Strange they first moved to the correct year and were still visible then one by a one a bit later changed to missing.   I know the clips are still there as I watched them to date them and didn't move them.  I think somehow imovie is getting confused as I put end dates before the start date (since it fixed the start date to be the import date).   The clips are shiowing up chronologically in the year I changed the end date to.  But all are now showing missing.  
Any idea how to get my clips back and get them properly dated???  It seems like some of my clips were properly dated so it is possible the problem clips were never dated correctly but I am pretty sure they were (and they were important milestones like my wedding and honeymoon -- the first events after our first camcorder purchase!).