For the last month my YouTube videos have had the same 3-4 Udemy adverts showing up at the start of every video and in the middle of many. It's driving me crazy! After weeks of seeing that Udemy guys smug face I just scream. After a bit of digging around I finally found what I was looking for, a way to get rid of the adverts. Pause the advert video and look to the bottom left hand corner where it says:
"Ad 0:28 (i) [link to their site]"
If you click the (i) you get the "Why am I seeing this ad?" popup. At the bottom of that is a link titled "Stop seeing this ad". Clicking that gives you a second popup asking why you want to stop seeing it. I picked "Repetitive" and then "Send". Boom. Just have to do that with each advert you don't want to see.
There is another way to hide video adverts based on their category. Check the page "Ads you see on videos" and click the "Ad Settings" link in the bottom paragraph. On this page you can turn off advert customisations so you just get random stuff that's not based on your searches and you can deselect specific categories i.e. no longer want to see videos about "Computers & Electronics". I chose the first method I described because I don't mind most tech related adverts. It's just the horrible Udemy guy over and over again led me to hate their platform!