Ok here is the answer :
one day youtube was bigger than google . but not now . because now google owns youtube : ) , which means that youtube company is a small part in google company : ) .
what google did is it found it self as you said only a search engine for information and also images , and they decided to do vedios , so they had buy youtube with 2000 Million Dollars : ) , just to link youtube vids on google vids sites , and then now google have a satalite which is google earth that captures the world from the space to make you see the world as you see it in google earth , and it have a universal gprs system which makes you able to navigate the world through google maps , and now google is the largest ever Advertisment portal . you will find this every where "ads by google" .
and if we will learn somthing from that , we will learn that an idea could be hundred millions of dollars in the future , and the IT is the future .