Apple Final Cut Express 4 - Manual (Page 579)

Chapter 38 Sequence-to-Sequence Editing 579
VII
Editing the Content of One Sequence into Another
Without Nesting It
Instead of nesting one sequence inside another, you can simply edit the clips of a
sequence into another sequence.
Editing Sequence Content Versus Nesting
To help you understand how it works, suppose Sequence A has the following content
edited into it:
If you drag Sequence A into the Canvas to edit it into Sequence B, the resulting nested
sequence typically has one video track and two audio tracks (assuming Sequence A has
two audio output channels).
Sequence A
Nesting Sequence A into Sequence B
results in Sequence A becoming
one clip in Sequence B.
Sequence B