I am certain there is a thread like "fla that works on any level or clip" for the guestbook...
You could do either
a) change the Num to wherever you are loading the movie .... but it will no longer work by itself
b) use "relative" targets, that is replace loadVariablesNUM('url',level,'POST') by this.loadVariables('url','POST')
Relative targets can sometimes be tricky - if loadVraiablesNum was called from a (button within a) movieclip, you would need to write _parent.loadVariables('url','POST') instead. The resulting movie will work by itself and when loaded
c) like b, but even more changes: use loadvars object .... you explicitly have to add code for all data you want to send and for all data you want to receive, and you get the ability to detect load errors; on loadvaribles style calls they just never return