tl;dr. Hillary didn't feel well on the 9/11 ceremony. She collapsed on her way when leaving. Media was then told that they are not allowed to shoot anything.
http://archive.is/Khh09
From NBC Pool Report: "We are told by the campaign that we are no longer allowed to shoot anything from the ceremony."

No cameras filming her at the time so no videos, just a couple photos.

https://twitter.com/RickLeventhal
https://twitter.com/RickLeventhal/status/774965031943438336
https://twitter.com/RickLeventhal/status/774966311260741632
https://twitter.com/RickLeventhal/status/774968879466549248
ARCHIVE:
http://archive.is/UbKoF

Articles:
http://www.dailymail.co.uk/news/article-3784098/Hillary-Clinton-rushed-9-11-memorial-service-following-medical-episode.html?ITO=1490&ns_mchannel=rss&ns_campaign=1490
http://www.express.co.uk/news/world/709501/hillary-clinton-health-9-11-ceremony-medical-episode-coughing-faint
http://www.foxnews.com/politics/2016/09/11/hillary-clinton-has-medical-episode-at-911-ceremony-source-says.html
http://www.fox5ny.com/news/204476383-story
https://www.thesun.co.uk/news/1764586/hillary-clinton-rushed-away-from-911-ceremony-appears-to-faint-amidst-reports-of-medical-episode/
http://heavy.com/news/2016/09/hillary-clinton-health-911-ceremony-video-photos/
http://www.breitbart.com/2016-presidential-race/2016/09/11/hillary-clinton-ditches-911-memorial-ceremony-early-reports-say-fainted-way-van/
http://www.usatoday.com/story/news/politics/elections/2016/2016/09/11/hillary-clinton-911-new-york-city/90223902/
http://www.jpost.com/US-Elections/Hillary-Clinton/Hillary-Clinton-reportedly-faints-at-New-York-911-ceremony-467455
http://bnonews.com/news/index.php/news/id5120