Music usage & Copy Protection
 

A local music artist (singer) has produced music c/d's in the past. Now she would like have a short music video produced by recreating short pieces (montage).

How long can a music piece be (legally used) without going back thru the liscensing processes again?

The notion that usage under some "x" length doesn't require licensing is an urban myth. While length of the excerpt used is mentioned in the law under the discussion of "fair use", AFAIK it is only in conjunction with the other fair use elements (such as for scholarly research, criticism, etc) that it becomes a factor. Any use for the purpose you describe, no matter how short, would need licensing. Of course if she is the composer and recorded the CD's herself so she owns the master use licenses already she can certainly use them for anything she wants. But if she's not the composer/publisher or own the rights to the recordings, you'll have to clear the usage through the rights owners.