GRRM held a short question and answer session afterwards and I think I will include what I gleaned from it here . . .
He is still writing AFFC. When he delivers it to his publisher, notice will go up on his website immediately (So I would say please don't write him to ask when it is coming out...that slows him down. ) The book will come out in England 2-3 months after he delivers it to his publisher and in the States 6 months after (sorry other countries...I don't know when it will be coming out for you ;( )
During Q & A, GRRM revealed what seemed to be the major reason for the five year gap. He said that he realized something. He had to deal with the reaction to Oberyn's death in Dorne. He thought of different ways that he could handle things. He could have just summarized what happened, without talking about it very much, but he did not want to do this. He could have decided that for some reason there was no reaction, or a delayed reaction, but the reasons he could come up for to do that did not make sense. So, he finally realized that the story needed to be told.
Someone asked him what RR stood for and he said "my middle names". Of course he has a great delivery so the room found that quite funny. He said he had been writing professionally since 1971. When he checked into a hotel as "George Martin" he was asked if he was the Beatles manager. I had never realized their manager had that name, and that was one reason he kept the RR. So much for folk who think he imitates Tolkien....
He was asked how he could remember all the details as he wrote several books over the years, since things are so complex. He replied "Maybe I have a trick head. I forget people in real life". Of course everyone understood. He can't remember folks he sees at conventions, etc. (Well...erm...he recognized me. Guess he has seen me enough). He explained that it was difficult because he had not done anything like this before and was now in his fifties. Previously his longest work was a single 450 page novel.
An anecdote that I thought was funny, still on the subject of memory. GRRM said that he sometimes forgets details, eye color may change, etc. He said that his dutch translater once caught the fact that he changed the gender of a horse. Heh. He said he was happy if he could just remember the horse's name and color, and does not have organized charts which keep track of the names of all horses.
And of course there are the people who want exact details. "They were long on the road" was the example he gave. He said he keeps things like distance and time deliberately vague. But someone would write inevitably write in and ask "How long were they on the road?". He just does not have rules for measuring the speed of a latent swallow, according to GRRM.
. . .
GRRM explained, as I said above, that the chapter he would be reading was one of seven from a Prologue of about 200 pgs in length.