Commercials on YouTube

I just bought a new hardened flash drive.  The manufacturer's Website pointed me to YouTube to watch their commercial for the product.  While I was watching the drive being driven over by a truck and beaten with a hammer I realized what a stroke of genius this was.  The company completely transferred the overhead of serving their video to YouTube.  Instead of paying the bandwidth overhead, they let someone else do it.  I wonder what percentage of YouTube content is commercial advertising?