As Mattk mentioned, it all depends on the size of the file.The most I have ever managed to send on a single email attatchment is about 5MB, and I understand this is due to restrictions my ISP (NTL) has.I am fairly sure most other ISP's have similar restrictions.
An easy alternative is to upload the movie to YouTube, and just send them a link in the e-mail. You can specify whether your movie is private or publicly available.
I did this when I wanted to send my family in the UK an 8 minute video of a brushfire outside our house. You can check the result here if you want: