Here are four arts and culture videos from public broadcasting partners around the nation.

WTTW's "Chicago Tonight" is airing a three-part series on the story of photographer Vivian Maier -- "the Chicago nanny who took more than a hundred thousand photos during her lifetime but never showed them to anyone. Now that she's gone, her photos have been discovered, and some say she may rank among the top street photographers of the 20th century." Here is part 2:

Off Book looks at the world of viral video:
"Viral Video is the signature phenomenon of internet media. Something akin to pop songs, these videos with irresistible hooks have saturated video culture online and have now evolved into a multitude of sophisticated forms. Whether rooted in comedy, spectacle, schadenfreude, cuteness, politics, performance, or deep meaning, the idea of viral videos have forever changed media."

Watch Off Book: The Worlds of Viral Video on PBS. See more from Off Book.

MN Original profiles letterpress artist Kent Aldrich:
"Visit Kent Aldrich's letterpress shop The Nomadic Press or browse his website and it's quickly clear that something's a little...different. Time seems to slow, small details take on weight, attention is paid. Aldrich began printing at a time when the practice was out of favor and now, over 20 years later, The Nomadic Press houses five presses, including two that were built in the late 1800s. An artist in his own right, Aldrich is dedicated to the hand craft tradition and imbues even contemporary designs with old world style."

As part of the PBS Summer Arts Festival, an exploration of the Barnes Collection airs Friday, Aug. 3. Here's a web extra:

Watch The Barnes Collection: "O'Keeffe" on PBS. See more from PBS Arts.