Sorry about your poor experience. Working on enhancing the UX as well as the instructions to use it, keep your eyes open for v2 :)

^To quickly address your complaints, the icon will appear in your browser URL entry bar, only for youtube.com sites (and automatically disappears for others, to prevent taking up unnecessary space when not in use). You can look at the screenshot provided in the description for more info on where it is. Simply type in your query, and if you see a :) face, your results will be highlighted in blue in the youtube timeline)