Why YouTube Pre Roll Ads?

Why YouTube Pre Roll Ads? A lot of people hate youtube pre roll advertising as they do interrupt us, are normally very annoying and just not relevant. However when you get it right, pre roll advertising can be a very effective way of generating high quality leads for a very small cost.
I recommend that any business owner gives pre roll advertising a "good go" because they could pay dividends and make bring in big returns.
Tom Breeze, Video Results.

[CopycatStudiosLA]

why is it that only huge brands hog the pre roll ad - i have never seen mom and paps on pre roll - is it becos those guys bid their vid off the chart high? if that is the case - do small biz have a standing chance of using pre roll at all?