The addin requires that Rollup 2 for MCE 2005 is installed. The
rollup isn't part of the "Critical Patches" section on Windows Update,
so it will not be installed automatically. This is the second thing
that should be checked when the addin doesn't work (the first, of
course, is that RegisterCommercialSkipAddin.cmd was run from the
Programs menu; it's OK to run this multiple times).
With that
out of the way, the next step is to turn on logging. Doing this is
easy. Run DVRMStoMPEGSettings.exe (from the Programs Group) and select
the Commercial Skip Tab. Check "Write Events", and then click Save.

Now
go open up the Event Viewer (Control Panel -> Administrative Tools
-> Event Viewer), and select the Application from the list of Log
names.
OPTIONAL:
I like to change the size of the Logs, so they can hold more data, and
configure it to auto overwrite as needed so I don't get errors. If you
don't take this step then make sure to turn off Write Events when
you're done.
Right click on "Application" and select Properties
from the context menu that opens. Then change the maximum size and
"Overwrite events as needed" properties, then click OK to save the
change.
Now
you're ready to start up MCE. When MCE starts up, the CommercialSkip
addin will write an event that notifies that it was successfully
initialized, if it cannot initialize an error message detailing what
went wrong will be written. If you don't see something at this stage,
either rollup 2 wasn't installed, or the addin isn't registered.
As
an example; this is the message that is written if the MSASSink isn't
registered or initialized properly when MCE opens. (You shouldn't ever
see this, it's just an example of something that can go wrong)
Any
time something interesting happens an event is logged (this is the
reason it's a good idea to change the configuration properties on the
Log). And when an error is written, it's the key to figuring out how
to fix the problem.