Visitor "request for password via form" plugin?

I want to share parts of a film showreel (embedded vimeo / youtube what have you) but some pages are private content (either rights issues or work in progress).

Therefore a visitor to that page wishes to view the content.
In order for them to do so I wish to ask them to fill in a short form and it will send a request for a password to view the content – the password will be sent to their email.
I do this almost every week with other sites (including wordpress!!) but is there a plugin available for WP that will achieve this for me on my own site? I’m had a good look round but can’t find one.