Edit MP4 Metadata with exiftool

I have an MP4 file with Title metadata:

exiftool movie.mp4

Which gives:

Audio Bits Per Sample           : 16
Audio Sample Rate               : 48000
Handler Type                    : Metadata
Handler Vendor ID               : Apple
Title                           : Movie Title

I want to completely remove this Title metadata. I have tried overwriting the title:

exiftool -Title="" movie.mp4
exiftool -Title= movie.mp4
exiftool -Title="" -overwrite_original movie.mp4

The command takes awhile to execute, but exits with:

0 image files updated
1 image files unchanged

What am I doing incorrectly? How can I view what the exiftool error is? How can I remove the Title attribute? According to the man page, MP4 seems to be a supported file type.

Thanks so much for your help!

Since the time of the original question, exiftool, as of ver 11.39, has gained the ability to create/edit a larger range of MP4/MOV metadata tags. To remove the Title tag from a video the original commands that @James Taylor used will work:
exiftool -Title= movie.mp4

Unfortunately, exiftool only has limited support for writing video files other than XMP tags. Run this command exiftool -G1 -a -s -title movie.mp4. I'm guessing that the title will field will be in the Quicktime group. And Exiftool cannot write to the majority of Quicktime tags.

Edit: Some quick research and I think ffmpeg can do it for you. You should do some more research to double check but I think this command would work:
ffmpeg -i InputFile -c copy -metadata title= OutputFile

I believe that -c copy will copy the streams without re-encoding and -metadata title= will clear the title field.
See multimedia.cx for more info.