Because WoW always comes before real life? Priorities are fun aren't they?
When he means priorities he means system processes priorities. A process in higher priorities will usually get more resources or something close to that, while lower priorities will get less resources.
Almost all programs are defaulted to the normal regular amount of priority to ensure stability of the system.
inb4lock(by admin)
what?
Most batch files are used to cause easily-made mayhem, i.e. deleting system32 and rebooting automatically.
Some are used for shortcuts or running programs with modified settings.