How I Use It
I've used this tool myself and with students in a variety of ways, but primarily to augment existing video or video mashups with pop ups providing additional information or hyperlinks. I've personally used it to create an introduction video for a MOOC, to augment a music video I created with "the backstory" and additional resources, and for splicing reflection vlogs from a Professional Development workshop. My students have used it to augment presentations, create lessons out of TED talks, craft back-to-school videos on the first day of school, and (my favourite) - annotate their final course reflection vlogs with links out to all their projects. As Mozilla Webmaker Fellow, I had the opportunity to develop some crowdsourced creativity projects, including 2 language learning / practice ones and a global poetry-focused experiment called "Glo-Bard". Sometimes things are buggy but my recommendation is to dave often.
I love the idea of Popcornmaker and it looks like they've added features, such as a collaboration mode. The fact that you can remix and build off of other videos is key. Mozilla Webmaker site offers many ideas for teachers to use this tool in the classroom. I do wish the user could have a more public channel such as YouTube.