I’m sure we’ve all experienced this to some extent, but I also feel like confirmation bias can play a large role here, so im curious. Is there actually something running in the background that boosts ads over actual content? Is there any literature or first hand employee (YouTube or similar) experience on this
You have in-between content caching servers. Ads are always cached as they are temporary and will almost always be served. Then you have the local Google webserver you connect to, which contacts a local Google CDN close to you. This CDN will have a cache of videos that are “trending” worldwide and in your area/country. If you ask the CDN for an obscure video, it will grab the video from the storage servers. The CDN will then start caching the video depending on the traffic it started to receive. This is why ads are always fast and why videos have different loading times.
I don’t work for YouTube but I’m an experienced webdev and this is how one would do it.