Don't worry about the videos at the start. You have ALLOT to do before you can do that.
first you need to understand PHP... then there are some things that i guess you will want as standard before you add video's and stuff.
Rolebased User login/logout
dynamic profiles - so people can change content
posting comments
uploading multiple pictures
user management for you to moderate with admin account
This doesnt even include the design of the website or the design of the database (very important)
so, start small and try something out in PHP... build it up a piece at a time, do the most simple and basic things first.
EDIT
jakare wrote:It's good to hear that everything i need can be found in this forum. 🙂
You could find everything here, but don't forget your best friends;
Google
PHP Documentation
*MySQL Documentation