The reason they don't do 5 minutes of straight ads every 12 hours is because you'd get people that just walk away, switch to another tab and mute Youtube for 5

The reason they don't do 5 minutes of straight ads every 12 hours is because you'd get people that just walk away, switch to another tab and mute Youtube for 5 minutes, or any number of other things that would end up with juiced ad statistics with no corresponding real benefit to the advertiser. Then, you'd get the response to that, which is ads you have to interact with to essentially tell the server you've seen the ad. I've seen this in mobile games already, and it's damn annoying. There's no way I'd want to spend 5 minutes doing that kind of thing.