I can vouch for this as well. I monitor traffic from my linux router/firewall and have noticed significant decreases in over all bandwidth utilization with ad blockers enabled in the range of 25/35% depending on what I'm doing. Although I use Disconnect and/or uBlock ,as Ad Block Plus is a bit more of a resource hog. During my normal pointless browsing sessions, when Im not doing anything work related and just following click bait for mindless entertainment. I noticed a roughly 20% directly attributed to video ads. This is much less when I am doing something work or hobby related as I generally avoid the news sites and stick to forums and technical sites for information. That said, even some of my regular favorites *cough* Slashdot *cough* have started getting worse with the ads. Fortunately unlike most sites as a long time registered user, /. allows me to disable the ad's.
For the record; I have NEVER in my life clicked an ad from a website that resulted in a purchase. I have only a handful of times, made purchases from email blasts when good deals were presented. Once from Tigerdirect, some from NewEgg during black friday deals, a couple times from REI, and once for a viagra, JUST KIDDING! :D I simply can not imagine how truly successful that style of advertising is successful when 99 out of 100 people I talk to about it say they hate it and avoid clicking that crap, on principle, because it is so annoying.