Having done a couple of DS106 radio shows with Jim Groom (which suffered rather from, erm, technical difficulties), the notion of the early video cassette recorder as a formative technology has emerged for me.
Here are some ways in which I think it was relevant:
It changed the film industry - home video was seen as a threat by the film studios back in the early 80s, with the fear that it would mean people would stop going to the cinema. This didn't happen, and gradually they realised that it was another very lucrative form of income. Many decent films got a second life on video, and an awful lot of crap ones went straight to it. Ironically, it is the protection of DVD rental and sales (the very things they fought against) that the film industry seeks to protect against the new interloper, the internet.
It created a new kind of aesthetics - this is my attempt at justifying my penchant for B-movie horror, but I think, that just as, say Dire Straits seemed made for CD, and Gladiator for DVD, so those 80s horror films such as The Evil Dead, The Thing and CHUD seemed to be the right mix of platform and content. Carpenter's The Thing was panned when it was released as being over the top, but I think he understood the type of aesthetics that worked on VHS.
It acted as a social object - I was one of the first kids to have a VHS, and so people would regularly convene round my house to watch films. We developed a library, a shared repertoire of dialogue, and a culture around the movies that we could watch repeatedly. We still went to the cinema, but being to see your collection of movies over and over, created a different type of interaction between school-friends.
It gave the viewer control - this was the main thing, it first of all liberated us from TV schedules or cinema listings - you could rent the film you wanted and watch it when you determined. But also it gave us control over the viewing process. You could fast forward, rewind, slow mo and pause. There were many films which we would skip to favourite scenes in (eg fight scenes in The Warriors), and particular ones we would watch in slow-motion (the head exploding in Scanners). This meant we were watching films in an entirely different way from that which was intended.
[UPDATE] The birth of read/write - I didn't include this originally, but Scott's comment below set me thinking. I didn't do much creating with the VCR, as cameras were still expensive, but on reflection, Scott is right to highlight this. Even by recording from the TV you began to make your own creation - for instance, I had one tape for artists on Top of the Pops, so over the years created my own compilation (I wish I still had that tape now). And in the late 80s a bunch of us hired a camera for a weekend and made a video for a friend's 21st, with a bunch of comedy clips and film pastiches. So, even if we didn't do much, this technology marked a significant change - that from consumer to producer, which is one that has come to define the modern age.
I think all of these have resonance with what we are seeing now with internet culture - the threat of new technology, loss of control, greater choice and democratisation of process. The home computer is often cited as the influential technology for today, but I reckon the VHS home recorder was more significant. It taught us how to play around, reinterpret and take control. And it had great big buttons you could operate with your toes.
(don't watch this clip of you're a bit squeamish)