Gravity Falls (found Comic Con 2012 promo of Disney Channel animated mystery comedy series; 2012)
Logo.
Status: Found
Date found: July 22, 2017
Found by: TGWTVHS 2.0
At the 2012 Comic Con, several then-new shows and episodes of shows were being announced, with some even having sneak peaks, such as Gravity Falls. This preview was once on Youtube, but it was taken down, likely due to copyright infringement. It has not been published officially in any way, however.
The promo reportedly featured clips from the first group of episodes (up to "Irrational Treasure") as well as a slightly different version of Dipper's cold open.
EDIT 29-07-2017: On July 22nd, a YouTube user by the name of TGWTVHS 2.0 uploaded the promo on his YouTube channel, saying: "[...] I didn't record these,[....] Somebody posted them on YouTube at the time, and I downloaded them. The originals are long gone by now".
Promo