I think you actually want two answers, the question you asked and "why
report it?"
The IDA Pro disassembler and the Hex-Rays decompiler are not only very
expensive tools, but they are very difficult to purchase. Due to
constant problems with piracy, these days they will only sell their
products to three areas; (1) governments/law enforcement, (2) very well
established corporations (typically well known security research
people), (3) very well established university researchers.
Typically, they refuse to sell to individuals, but there is a fourth
class of customers who are individuals; very old customers like me who
have a perfect track record of maintaining possession of their copy of
the software.
Every copy of the software is custom compiled and watermarked so it
is traceable to a particular person. Every database created by the
software is also watermarked, so when someone who is not a licensed
customer publishes a database (.idb), the software can be traced and
the account will be terminated (i.e. no further purchases allowed).
When someone does something blatantly stupid like disassembling and
decompiling skype then publicly making all of the files available, it is
fairly certain that they are using a illegal copy of the software. They
do not understand what they're doing. They do not understand the tool
they are using. And they don't have any respect for either the tool or
the work of others. --All of this loudly screams PIRATE!
The pirates either don't know about or don't care about the watermarks
in the databases they create. They don't realize that publishing a
database is discouraged. I've never heard of a case where a database
watermark was successfully forged (i.e. pin the blame on someone else),
but a cracker named "Quine" once successfully removed the watermarking
in IDA back in the late 90's.
The "correct" method to publicly share the research work done in IDA is
to dump the database to an IDC script (an internal language), then
provide the IDC script and the target binary. Customers know this, or at
least they should. With that said, friends do toss databases back and
forth on occasion, but that's a matter of trust between friends where
both of them are customers. Some people in the InfoSec and AntiVirus
crowds exchange databases, even across competing corporate lines since
they're all working together towards the same goal and they've known
each other for years.