There's little doubt when Google paid billions for YouTube they believed that they could extend their text-based advertising business model to video.
With the purchase of Doubleclick they partially managed this, but only if the metadata reflects the visual image being shown.
But matched video advertising totally eludes these self-styled geniuses. You can only 'qualify' for Google video advertising if you serve huge numbers of users, and then only in the US.
This means that YouTube is just another medium selling its ad and sponsorship slots to media buyers. It seems t0 have done quite well at this, but it's a million miles from the original business model, I suspect.
Another issue is that the content is full of dross and pirated content, places where no sane brand wants to see its ads. Media is all about context, and the YouTube context is like one of those vast trash dumping sites.
So now they're trying to reinvent themselves as a video management platform, but the baggage is scary and, as it happens, Google produce dreadful technology platforms, as the failure of pretty much everything apart from their ad platforms shows.
The reality is that text is pretty simple to decipher, but images, and especially video, are very difficult to codify.
Google may have built smoke and mirrors around its business, and might have built a massive business on the back of a very corrupt and opaque core proposition, but YouTube remains a total and abject failure as an extension to their core business.