Many email services have an attachment limit if 20mb and some an attachment limit of 10mb. That means that video is rarely suitable for emailing. Options:
Upload it to a sharing site like YouTube or Vimeo and email a link - these will allow the recipient to view the material onlne.
Upload it to sharing services like Dropbox or YouSendIt and email a link. This will require that they downoad the material to their machines to view.
If this is from your point and shoot camera then they are already massively compressed, so unless you fancy reducing them to the size of a postage stamp, it's very unlikely.
To compress: see what you can get from iMovie
But really, movies are just not candidates for emailing. Check out Drop Box. It's very, very simple to use and free for something like 2 gigs of space