Nucleophilic substitution Sn2 versus Sn1

I have made a little movie to simply distinguish between SN1 and SN2. It is similar my youtube video shown ( no music though- if you want that, just use the youtube!) I have not added commentary, leaving that to the teacher. If required, I could add it.
Update: now sn1 improved so it is more simultaneous.
Please note: in order to provide a rich interactive experience, my interactive resources are mini-web sites local to your computer. After unzipping, they comprise a folder containing the main .html file and another folder containing the graphic resources and my coding to make the resource work. Double click on the .html file and the resource will work. If, however , you move or delete any of the files from this hierarchy, the resource will not work.