Error copying file to external HD

Tried cloning the file via SuperDuper! or CarbonCopyCloner (version 3.4.7 is still free and available for download here and works with Mac OS X 10.6 Snow Leopard, Mac OS X 10.7 Lion and OS X 10.8 Mountain Lion)?

Question, is it a USB 3 external hard drive? Is your MBP one with USB 3 ports? I've had a few USB 2.0 Macs that seem to really hate USB 3 external disks, sometimes even out of the blue, they'll copy a few gigs worth of files then suddenly BAM, no data can be read or written.

"I'm guessing for some reason that file is just corrupt. Very strange as it opens fine in adobe premiere and quicktime!"

Is a "mov" file "one file", or is it actually a "container" filled with several files?

To ascertain this, go to the finder.
Then, RIGHT-click on the un-copyable file.
Does a contextual menu appear with the option to "show contents"?
If it does, choose to "view the contents".
You may find a number of items "inside". If only one of them happens to have some corruption in it, this may prevent the entire "mov file" from being copied.

Simple solution:
Unless that mov file is particularly important to you, you can just delete it.

More complex solution:
If you find the file to be as I described above (i.e., comprised of several "internal files"), you might try "manually copying" each and every component individually. If you discover one file that can't be copied, ignore it.
Will the "copied file" still run without the bad internal file?