I have 2 VHS tapes (need to transfer to DVD) just for that reason, what you know beforehand is admissible exculpatory evidence, but you have to be able to prove (tangible proof) you had the knowledge before an indecent (explained to me in depth by the local prosecutor in my home town while riding on patrol with a sheriffs deputy buddy) not just say "Oh yea I read an article about that once".
I have "DEADLY EFFECTS; Wound Ballistics" with William Facler(?) head of the Army's Would Ballistics Laboratory; to explain (if needed) why the deceased has multiple bullet wounds. I also have a copy of a police training video "SURVIVING EDGED WEAPONS" don't have the specifics as it is a copy.
I have them, I can prove I had the knowledge before an indecent and "should" be allowed to show to a jury should it go that far. You need to print those articles, put them in a safe deposit box if you have one (maybe even have notarized as to date) download to you computer and NEVER modify the original so the date stamp on the file does not change, make another copy to use to copy segments from or if you want to modify something (bold, hi-light etc).