When you select the "attach file" option, a browser window appears, allowing you to choose the files that you wish to attach. In the lower region of this window, there is a bar that allows you to select which type of files you are viewing. Make sure that the option is set to "All Files," so that it will include the available video files, as well. As such, you should be able to find and attach videos directly to your e-mails. There is, still, another aspect that you should keep in mind. Most e-mail providers impose a rather strict limit on the size of the files that you may attach to your messages (around 20-25 MB). Be sure that your videos do not overpass this limit, so that your message should be sent without any inconvenience.