Installing WordPress

I have wordpress installed already on my website but im wondering if this is possible..

For example my main website is http://www.example.com/wp-admin

but can i install another wordpress on the same url but for different stuff example: http://www.example.com/videos/wp-admin

so i have 2 different accounts, would this make my website main page load slower also??

PLEASE HELP!

THANKS IN ADVANCE SORRY IF THIS IS A SIMPLE QUESTION BUT IM NEW TO THIS.