VideoANT is a free tool for collaboratively annotating videos. I first wrote about VideoANT back in 2010. Recently, as I learned from Nathan Hall, VideoANT received a major facelift that makes it easier to use than it was before. The first improvement to note is that the service is now built on HTML5 which means that Flash is no longer needed. The second major improvement is improved ease of annotating videos.
Via Gumersindo Fernández, Ana Rodera