useful for teachers making clips to analyze in class; "personalize any video with your story. With visual spotlights, you can narrate your personal videos, add captions or subtitles, or comment on any scene."
how to create hotspots with popup notes on Flickr. Very useful for image analysis and assignment requiring students to comment on social aspects or formal aspects of image; or to formally critique them.
Firefox extension offers an addictive way to search via categories or keywords or happenstance; you train it, with thumbs up or down on sites, so it learns your tastes; I prefer searches on keywords so far, and have had little desire to "network"