[NoZebra120vClip]

I was fascinated by the concept promoted by Pandora: "digital DNA" of musical works. It was an exhaustive list of properties applied to each song they played, and it fed into their recommendation engine so that songs could be typed and matched with more stuff we wanna hear.

It failed me miserably.

Digital DNA, or at least its implementation on Pandora, was woefully inadequate in determining my motivation and reasons for selecting songs in a list. I created a Lenten playlist of penitential hymns, and the cardinal rule was: "NO ALLELUIA" which is not vocalized at all during the Lenten season. Well my recommendations were liberally sprinkled with joyous Easter shouts of the A-word, and my experience was ruined.

I may select songs based on particular lyric themes, seasonal considerations, bands based on their particular location or affiliation; things like that. Recommendation engines just have this kind of sledgehammer that goes "Oh! You like <Heavy Metal>! Here's some more <Heavy Metal> for ya!" when my use case doesn't even care about genre, but I was looking for lyrical themes or topics.

Also unlike Pandora, YouTube has one big firehose of recommendations. It is unable to segregate them within a playlist or a particular session for some purpose. The only way to isolate recommendations is by account or incognito, and that is one reason I have 3 separate personal accounts for different purposes, so that my main account's activity does not pollute the interests and recs of the special-purpose accounts.

[stametseater]

Ah right, I see what you mean. Supposing I tried to make youtube only show me videos of red trains, it would probably fail. It has a limited number of content bins and probably doesn't/can't synthesize new bins on the fly for individual users.