0001.MP4 0002.MP4 ... 1230.MP4
The problem with this approach is that the original filenames are gone for good. What if we wanted to keep the original names? The obvious solution would be to copy the files, then rename the duplicates and work with them, then delete the copies in the end. But when each video file is a few hundred MB, copying these huge files would take too much time and disk space, so we need something smarter.
How can we "copy" files without actually copying them? We can create links to the originals. These are like shortcut files but they appear as if they were duplicates and they take next to no storage space! You can move them around and rename or delete them without affecting the source files. (But if you change their contents then the originals are affected).
If you are on older windows (pre Vista) then the only solution is a hard link, but these have certain limitations, e.g. you cannot hard link a file from a different disk (partition) or removable storage. If you are on windows Vista/7/8, the best choice is a symbolic link (Edit > Paste special menu command). Even these don't exhibit 100% clockwork operation as you must first elevate yourself to full administrator otherwise symbolic linking fails.