RE: video patterns

I ran some stats on the distribution of file sizes on a Windows NTFS
drive extracted from a computer that had been in use for several
years.  Windows XP was installed.  There are 44,744 files on the
drive, consuming approximately 18G total.

I put together a quick spreadsheet which calculated the number
of bytes of slack space, given a 4096 file allocation unit.
Here are some results:

0.77% had zero file length (thus 4096 bytes of slack space)
7.37% had a non-zero file length that is an even multiple of 4096
      (thus 0 bytes of slack space)

Slack Space
w/ at least N bytes     Percentage
32                              92.34%
64                              92.07%
128                             91.50%
256                             90.29%
512                             86.87%
1024                            79.92%
2048                            62.91%
2675                    49.99%

Thus, if we were to look at the last 256 bytes in each file block
(on this particular collection of files), we'd be looking at roughly
90% of all files on the system, where the majority of the remaining
files didn't have anly slack space at all, and therefore must be
ignored anyway if we're looking to match the last N bytes of
slack space.

The main reason that the figures work out this way is many files
on a typical system are small.  On this sample, 44.5% of the files
had a size of 3840 or smaller (at 3840 bytes, there is 256 bytes
of slack space remaining).