varDUppaluri

I've read all the replies to your post and I have one thing to add.
All that people typically provide are photos together, POE stamps (Port of Entry) on passports to prove travel, boarding passes, chat logs, emails exchanged, telephone bills etc.
You have to be very prepared for the interview also. Its not always what you show on paper. You have to be quite confident in your answers. Look up interview questions on the internet and prepare yourself really well(I'm sure you did this already, try harder). 1000 pages of chat logs seems too good to be true. I had around 700 pages of chat/email/text message logs, but I picked a few from every month and reduced them to 40 pages.
Answering your other question, you can't provide videos as proof because any kind of memory devices (CD's, DVD's, pen drives etc) are not allowed into an american embassy.
Looking at what happened in your case, it just looks like the CO is not convinced with you rather than the content you provided. So be very prepared.

Hey, I think it really depends on the consulate. we didn't have to get ours notarized and I'm from india. when in doubt I think the right place to get it cleared is to call/write to the consulate you would be attending the interview at. All the best!