What it is: Critical Past is a website I learned about today from Tom Boito’s great blog EDge 21 in his Catch of the Day.  The resource is too good not to share again here!  Critical Past is a collection of more than 57,000 historical videos and more than 7 million historical photos.  All of the photos and videos are royalty free, archival stock footage.  Most of the footage comes from U.S. Government Agency sources.  All of the videos and photos can be viewed for free online and shared with others via url, Twitter, or Facebook.  The videos and photos…