I suspect the answer to all this is more nuanced than video vs written. I think there are a number of elements in play and what it does do is reflect the greater diversity of the hobby. It also talks to the very good point made by etotheipi about the media best suited to the task.
I started a blog just over four years ago and page views have grown exponentially each year with the total number of page views about to hit 500,000. That strikes me as a fairly healthy sign that there is life in blogging yet. However a deeper analysis shows that certain types of posts are much more popular than others.
The 'what I painted this week' type of post, once the mainstay of blogging, draws very moderate interest and nearly all views come within 24 hours of posting. I think blogging has lost the big numbers of followers that would have come to blogs to see this to social media, with Facebook, Twitter etc doing a better job of fulfilling that role. It doesn't mean bloggers can't do it but I suspect it's the sort of traffic drop off that people like Yarkshire Gaming are referring to. That's not necessarily a bad thing, I think social media is fantastic for this and I see much more from a wider group of people in the hobby than I might have done otherwise.
Where as my posts about what I've done recently have low interest, my game reports and AARs have a lot of traffic, as do tutorials on making terrain; articles about game tactics and reviews. Not only are the number of page views considerably more (the most popular post about Chain of Command has over 20,000 page views) but the traffic remains consistent over a long period of time.
The most interesting are the game reports. What I find most relevant here in relation to the discussion about videos is the average time spent on each article by a viewer. In general the game reports don't vary much when it comes to this and most average 7-8 minutes. I can see how this would be attractive to someone who doesn't have time for a 2 hour video. While a video offers the option to fast forward or rewind it's not the same as scrolling back and forth through a web page, particularly if you are a speed reader. Perhaps best of all the reader does it as his or her own pace, I don't dictate the pace at which they are read, the reader does (which was exactly etotheipi's point).
Does that make it better than a video? No, just different. Clearly videos work for a lot of people and I'll happily watch some myself. That said, after working in the film industry for 25+ years I have a very low tolerance for poor production values, unedited pieces and wavy hand-held camera work (fine for the odd sequence, but not for two hours). I can see from other posts here that I'm not alone. But, to be honest, that's no different to my tolerance for poorly written blog AARs that make it near impossible to understand what is happening in a game because they are difficult to follow and poorly illustrated.
I think we naturally gravitate to those people whose work appeals to us and the others we leave aside, but as tastes and tolerances vary that leaves the field open to all comers.
The number of videos are certainly on the rise but I'm not sure the majority draw the same number of subscribers and viewers as blogging managed 10+ years ago. There are a few factors – quality of videos, as has been mentioned; length of videos (how many 2 hour videos can you watch in a day? a week?) and lastly, the suitability of video as a medium to convey information. From what I can see from viewing and subscriber numbers it's the 'how to' videos' that are most successful – how to paint, make terrain, play a rule set.
I'd be very interested to see analytics that show how many people started viewing some of these videos against how many stopped before watching before it finished. Google Analytics tells me what percentage of people exit my blog after viewing each article, it also tells me the average time spent reading each post. The latter is the most interesting to me, if the average reading time for an article is less than say 30 seconds then I know I must have lost most people very early on.
The good thing is that at the moment we have an embarrassment of riches where you can choose the media that suits you best.