The exact method will vary depending on the OS and platform, but generally the first thing authorities will do is use a disk cloner to create an image for forensic purposes. Once they have the cloned image they can use a variety of techniques without modifying the original. This ensures that the original system can be re-cloned if the copy gets damaged. It also ensures that an original unaltered image is available to both sides in the event of a court case.

I think that what they were worried about is that it encourages people to record their station with a PVR and then skip the advertising.

TIVO in Australia has ad skipping disabled. To carry the new "Freeview" logo and gain access to the enhanced Freeview EPG (when it becomes available!) an STB cannot permit ad skipping.

A non-freeview box with IceTV gives both ad skipping and a good EPG

From my reading of the decision, it looks like this would apply to the train timetable (but IANAL).

What the court has said is that although collections of facts can be copyrighted, the question is to the degree of originality in the expression of those facts.

In the case of the TV guide, the alleged infringement consisted of two pieces of information; the program title and the time of transmission. The title is supplied by the program's creator; not Channel 9 and the time can only be expressed in a standard way (Channel 9 could hardly claim copyright of "7:30 pm"); Channel 9 has therefore not exercised creativity or originality.

The train timetable is much the same. There are two pieces of information; a station name (which is much like the program name) and a departure time. Cityrail has not exercised any creativity or originality in the expression of this information.

It is the lack of originality of expression that results in the information not being copyright; it is not a fair use claim, so the amount of information copied does not matter.