In Keynote, Preview and other applications text (and thus Chords and Scales neck diagrams) is inserted in floating and movable text boxes which can be placed and arranged anywhere on a page.
In Pages word processing documents you can choose whether you insert neck diagrams inline as regular text or in floating movable text boxes as shown in the video.
As already specified (→ Library → Lyrics sheets) Spotlight Search offers a quick and easy way to insert chord-, scale- and arpeggio diagrams into your documents. As you type Spotlight builds a list of every match it can find by tracking the keywords, descriptions and tags applied to the Chords and Scales snippets.
As shown in the video choose Am7 penta V.rtf and drag and drop it directly from the list into an open Pages Word Processing document. Pages ’08 and ’09 import files in Rich Text Format (.rtf) and preserve their formatting.
To insert a floating textbox with a movable neck diagram hold the Cmd (⌘) key while you drag and drop.
In the Wrap pop-up menu in the format bar choose None to deactivate wrapping text around the floating textbox. Alternatively open the Wrap inspector and uncheck Object causes wrap.
You can edit the pasted diagram by applying text features like font-size, color, background-color or shadows.