|::||Colons are used to indicate the prolongation or stretching of the sound just preceding them. The more colors, the longer the stretching. On the other hand, graphically stretching a word on the page by inserting blank spaces between letters does not necessarily indicate how it was pronounced; it is used to allow alignment with overlapping talk.
The words "ri::ght", arrow 1, or "deci::de", arrow 2, are more stretched than "oh:", arrow 3, even though "oh:" appears to occupy more space. The "oh" has only one colon, and the others have two; "oh:" has been spaced out so that its brackets will align with the talk in the line above with which it is in overlap.