If you teach middle school students in Maine, or if you are lucky enough to have some good technology in your school, you might be lucky enough to have iMovie or Windows Movie Maker at your disposal to edit videos. I do know, however, that there are many teachers and students who don't have access to these two programs and also don't have permission to load programs on their machines. Well, there are some online video editing tools that offer some solutions. I don't see them as a substitute for something like iMovie, but if you'd like to get into simple video editing on the cheap (as in free) here are some suggestions. One note of caution, you should ALWAYS review a site personally for appropriateness before using it with a class since it is created by users even though the sites below don't allow adult content to be posted.
http://www.jumpcut.com This is the best one I found and if you have a Yahoo account (free), you can merge it with Jumpcut and share that login. Jumpcut lets you use your own video and audio. You upload them to the site from your computer, a cell phone or even by emailing the files as attachments to a personalize address setup in your Jumpcut account. It also lets you bring in video and pictures from Flickr directly. You can also explore publicly available video and pictures on Jumpcut and add them to your shelf using the simple "grab" button when you are logged in. After you have your video, audio and pictures, you can do some common editing tasks like cropping, cutting, and adding title screens right on the site mostly by dragging and dropping. Jumpcut also lets you add some effects and transitions. Videos can be shared publicly shared privately with only the people you invite to view the video. You can share videos easily by embedding them into other types of sites (blogs, facebook, myspace) or by emailing a link to someone. People can rate your video and even leave you comments if you'd like. All in all, this is a great place to start playing around. Here is a link to short funny video I made with it awhile back starring friends of ours and their son.
http://eyespot.com This website has many of the same features as Jumpcut but not quite as many. You can upload you're own video but not audio. You can "remix" other people's publicly available movies. You can also trim a movie but there aren't any other editing features (no titles, transitions, effects or music). It's a good service to use if you just need to share a video and want to narrow it down to the clip you want shared. Sharing options on the service are good. It integrates with several online blog services and sites and even lets you download the video to several formats and devices, including iPods. Public/private sharing allowed and comments and ratings are here too as well as mobile phone and email uploading of files. Here's a sample video of my daughter two summers ago.
http://Motionbox.com - Looks good. You can upload from your computer, cell phone or by email. You can edit original videos, join video files together, share by email or embed. The only editing it lets you do is just really trimming video, but it does let you select a part of your video to send or save by itself (effectively cropping it). There are the same private/public sharing and commenting options as the rest as well and it lets you save up to 300MB of video on the site for free. Here's another sample video to show you.
http://photobucket.com This lets you add video and pictures with some editing (mostly cropping). They have borders and transitions to use but the audio available is from their library and you can't add your own audio. Embeddable and sharable. You can make photo slideshows very easily here. Photobucket lets you mix multiple videos together as well. My major problem with the site is that it asks for a lot of personal information (including cell number), although it let me register without providing some of it. I feel like this site is more distracting and commercial oriented than the others, so I didn't really like the feel of it by comparison. Still, worth a cautious look. Here's a sample video of my daughter ice skating this winter.
Viddler.com- This site doesn't let you edit your video but if you want to let people comment on specific points within the video, it gives users a "+" button on the timeline where they can leave a text comment at that point. You can get notified by RSS of new comments on the video. Also, when you share the link to the video, you can share the whole video or jump right to the current frame. Good way to have a discussion around a video clip. See a sample here (not my video) hover over the timeline on the bottom to see comments.
Kaltura- This site aims to have people work together to add short video clips to a common film. I found a good example of how this might be done with drumming, however I found the pop-up ads on the video window very distracting. Still, it's a neat model to think about how to collaborate easily with video.