File Upload Script

I need someone with an upload script. I need to create user accounts for my teachers to upload Video Files. Needed: 1. Ability to create user accounts with password 2. Ability to upload large files up to 100 megs 3. Upload multiple files 4. email admin when a new upload has been made 5. admin is able to download files from user accounts I want to use a script allready made and not build from scratch.