The sheer amount of ads on youtube is what's making people use ad blockers. Two unskippable 15 second ads after one minute of a ten minute video is ridiculous.
Honestly that's the uploader's fault. They're too lazy to manage their ad locations and let Google do it for them. Google always adds way too many. I make sure my videos never have more than 3 in 30 minutes, and I craft the videos so that they have precise break points like old school television. You'll (almost) never see an ad on my videos that interrupts something important. It takes so little effort to do this.