You have to throw in a few seconds near the beginning of some half dressed person just to keep them on their toes - something that would get missed if you fast forward, which is exactly what they'll do. Audio's a good idea too, since they have to listen for something objectionable.
Almost all modern entertainment media is locked down by copyright, so there's no way to gauge what culture might be like if a significant portion of it were public domain. Books are an exception because there's a significant number of public domain works that are still widely popular - so it makes sense to study copyright's effects on culture through books. I suppose you could also look at the still thriving market for classical music, where the vast majority of work they perform is pre-copyright.
If copyright terms had not been retroactively extended, there would be a significant body of 20th century films and sound recordings in the public domain to make a comparative study. Unfortunately, we may see the 20th century fall into the public domain until the 22nd century.
You praise all the progress of the 20th century but who's to say that progress wouldn't have been improved if things were different? For one thing, maybe a handful of multi-national corporations wouldn't own the vast majority of our culture, and maybe more than just the most economically viable material would still be available to us.
Since the internet became mainstream we've learned that there's a vast amount of culture that was being filtered out of the corporate system that existed before. The 20th century method of big companies controlling popular culture probably wasn't the best system - it was just the most efficient at the time. It hinged on controlling access to mass production and distribution.
The internet gives creators access to these things that before they could only get by giving up their copyright and control to a handful of major players if they wanted to participate in mass culture.
The thing is that things changed long ago. Copyright was overhauled, and terms were extended to extraordinary lengths, and orphaned works became a thing. Where was the data that said all this would be beneficial to the public?
If that were true, then why does the number of available books in 2000 and 2010 match 1910's levels? It's not as if books have suddenly become the dominant form of entertainment. It looks much more like publishers are only focused on their latest and most profitable books, while keeping most of their back catalog off the market and out of print - a century of culture locked in a vault.
But it is worth considering how many books were actually published each decade, if such data were available. I suspect it would be the opposite of what you propose - with far more books published in the 20th century than the 19th century.