Your question is based on the premise that definitions of quality survive changes in media technology, they don't.

Three examples:

1. Lee de Forest, one of the (dubious) pioneers of radio, thought radio would take classical music to the masses. Nope; classical music retreated to an elite, premium and marginal market, and "pop" culture which was previously too local and fragmented to travel far, took over and reinvented itself.
2. Neither folk theater traditions, nor elite theater traditions, survived the move to movies. The focus shifted from quality dialogue to overall quality scripts. Actors with powerful 'histrionic' (the term seems dated, doesn't it?) abilities gave way to those capable of the kinds of understated emotion and silence that camera close-ups can turn into moving narrative.
3. In Western dance, for complicated reasons, the delicate movements of classical ballet gave way to the bold and primal moves of modern dance in the early 20th century. Much larger audiences and venues were one reason: many audience members were simply too far away to see delicate movements. This is a rather weak example, because this shift had bigger causes. Still.

If you analyze these examples, you'll see that when the medium shifted, suddenly marginal content producers gained great leverage, while previously influential content producers were marginalized. The new medium amplified and magnified different things, and those whose artistry thereby became better showcased, won.

In each case, the early experiments suffered quality problems, often due to vestiges of the old forms hanging on, but eventually the medium found its mature voice (Elvis for radio, Brando for movies, Isadora Duncan for dance).

This is the theory of disruptive innovation at work in content, rather than technology. There are significant differences between the two varieties of disruption, so don't apply Clayton Christensen's models of disruption out of the box.

That caveat aside, we can draw two lessons from history:

1. Do a theoretical analysis of what the new medium (a la carte, on-demand video) amplifies and what it shrinks. Include the effects of delivery technology such as the huge range in screen sizes at work (wall displays to cellphones)
2. Look at the margins of culture to find the types of content that are in fact doing well in a la carte mode. Types of content, not types of content business model. Is it blooper videos? Mozilla's Firefox webcams? I don't know. I don't watch much online video. But I expect somebody knows.

Put the two together and redefine what "quality" means in the new medium. Identify the early pioneers whose students might turn into Presleys, Brandos and Duncans. Figure out what makes them special.

The business model will take care of itself.

There is an additional effect to be considered: the "long-tailization" and fragmentation of media.

This is a force that is hitting everything, not just video content, so it is a structural shift. Fortunately, the effects of this are actually much easier to predict: study the age of fragmented local popular (non-classical) cultures before the age of mass media. Look for commonalities. I bet those will reappear in some form. For example, the folk theater traditions of all cultures have certain strange similarities that might be worth studying.