Need media sharing web-app, control access by group

I am trying to find a good media sharing web app. Something that will let instructors upload audio or video files easily. And I need to let restrict access to the files to only the students in the class.

I have tried PHPMotion, and it's great for the uploading and sharing part, but it's a way of sharing files with everyone. I need to restrict access by groups.

This is my wish-list:

Web based.

Open source or inexpensive

LAMP

Flash player.

Automatic conversion to FLV

Easy to use for non-technical people to upload files (people for whom FTP is too complicated)

Accommodate streaming large media files, not live streaming but letting the user jump to the middle without having to download the whole file.

Ability to limit access by group.

Allow download of media onto portable devices.

LDAP authentication

Easy HTML embedding of player

I know I want everything.

PHPMotion is the closest thing I have found so far. It's easy to upload and does conversion to FLV. I suppose I could hack it with some access controls, but I'd rather not.

Is anyone aware of a flavor of wiki that could handle media file sharing using groups?

thanks

From stackoverflow

• PHPMotion was probably the closest thing I could find.

  In the end we went with Adobe Flash Media Server and we'll write our own access controls.