We often deal with companies that have little experience with digital files. Often we courier a hard drive to them (either ours that they can return or we invoice them for it) BUT you need to ensure it is compatible with mac and windows. Vimeo is a good site to use for high quality video too. I’d say it’s important to educate your clients on how to access video. Perhaps have a “How To” document ready to go as an attachment with emails you send?
http://www.corporatevideoaustralia.com