Chuck,
Some of the most valuable stuff I have seen on youtube is like the Evidence of Revision.  The actual news clips from that day and in the days after.  Like how they found the German Mauser rifle FIRST.
I had no idea that for days the news anchors were naming that gun as the assassin's rifle which it probably was one of them anyway.  Also if you can get photos that are not government issued by eyewitnesses.  There is one that proves the Zapruder film was altered.  I think it was one taken by Phil Willis.  It shows the limo just slightly after it turns onto Elm street from the front.  You can clearly see JFK with his hands up to his throat, yet in the Z film he doesn't start to do this until after they pass the street sign. There is also a web site that has 3 different Mannlicher Carcano rifles that the government says were Oswald's rifle.  Some were taken at the Dallas police station, some at the FBI. You can actually see that they are built completely differently.  There are even 2 that have the same serial number!  And the serial number has differences in the type.