Scenemaker.net looks like a really handy tool. It allows you to create your own channel and capture just the parts of various YouTube and other online videos. That way you can just show your students the parts you want them to watch. It also gives you an 'embed code' so that you can embed the video clip into your own blog or digital materials.
This is a nice way to grab and edit online video without having to download it onto your own computer and break the law.
Also helps to stop your students from wandering off onto other unsuitable stuff.
Hope you find it useful