I am sorry dude but You just way off anything, you have made no effort to even check on anything so I am not even going to bother linking countless articles, stories, even TV documentaries about it.
Your very wrong, sorry but you are, Porn chose VHS and pushed it to the limit before the movie industry becuase from start to finish in terms of production vhs is cheaper, and then movies followed etc.
While everyone pushes for new tech in media the porn industry is the one that chooses it and everyone knows the gaming industry and porn industry are large then the film industry.
You even make the point with the comment about the net - porn there first and the movie and tv companies only just starting to get into it years later.
Bet you anything as well pc game format of the future - hd-dvd again becuase of the costs! and again bigger then the movie industry.
Go on then.. lets see some links.
Infact, ask your parents, uncles, aunties, anyone old enough to remember when VCR players came out & ask them if you could buy porn off the shelf to watch or how easy it was to get hold off.
Back then, it was either in a brown paper bag from a sex shop, or from some dodgy bloke down the pub who also had all the latest hollywood blockbuster movies... or some back street cinema.
There was very little between Betamax & VHS, the only difference was the size of the cassette & VHS allowed a higher running time. Again, nothing to do with porn pushing it.. they just adopted VHS early... Quality didnt matter as they was shot with some old piece of camera. It was about getting the stuff out there.
Heres a quick one that back up the recording time..
I was around during the war, my family had a successfull chain of Video hire stores. Opened the first in 78 & we stocked very few betamax videos, even back then from the off.
http://en.wikipedia.org/wiki/BetamaxPorn will adobt whatever media is available the quickest & cheapest to get their stuff out there. Doesnt mean they actually the new media to their full capabilities & quality (though I dont know anything else that used the camera angle button on the dvd ;-))