Actually, you(or others) should not be downloading movies via mIRC feel free to search these forums for other such threads regarding it.
On IRC it is usually not possible to trace someones' nickname via their IP, however in certain countries that allow it, it is possible for legal services such as the FBI to trace users via their IP and in America you will probably have heard that alot of people were taken to court for downloading via applications such as Kazaa, the same can be done via IRC.
Please also note that there is a difference between mIRC and IRC, mIRC is a piece of software that uses IRC protocols and technology.
Eamonn.
