A bit of an update on this issue, since we've been testing to see if there is a work around.
Right now it appears that only videos hosted in ARIS count toward this "break" limit.
I have two test scenarios right now, one where all of the videos viewed are hosted as media in the ARIS game, and one where all the videos are hosted externally on a server and embedded in plaques with HTML. Both of these scenarios have 20 videos each.
When viewing the ARIS hosted videos first, I am able to watch 16 / 20 of the videos. When I then try to view any of the externally hosted videos, none of them will load or play. I am still able to view the ARIS hosted videos I have already viewed, but no new ARIS or externally hosted videos.
However, when I try viewing the externally hosted videos first, I am able to watch all 20 externally hosted videos, and then 16 / 20 ARIS hosted videos before hitting the "breaking" point. When I then try to go back and watch the externally hosted videos, the external videos are now broken as well and will not load. If I try to rewatch the ARIS videos, I am able to rewatch any ones that I was able to play before video playback broke.