To tag a movie, select it in Clipstart and press the "t" key. Type tags separate with a comma, such as "trip, family, new york". Spaces are allowed in tag names. Press the return key to finish tagging, or press the tab key to cycle to the next movie to tag.
Here are a few keyboard shortcuts to help you get the most out of tagging:
T - Edit tags.
⌘⇧C - Copy tags.
⌘⇧V - Paste tags.
⌘⇧⌫ - Clear tags.
The copy, paste, and clear commands are especially useful for stamping tags across multiple selected movies.