Upon completing T1C hunters were rewarded with the newest image. This GIF temporarily appeared in place of the password entry until it was supplanted by Wallpaper_Brown_Eyed_Girl:
There is a single known clue hidden in the GIF. Each of the three brief frames at the end has a hidden digit. The digits are 3, 2, and 5. Greek mathematician Euclid was born in the year 325 BC; As he is the father of geometry, this clue pointed us toward a geometry related solution.
Using a threshold adjustment layer with the threshold set to 255 is sufficient to clearly reveal the hidden digits.
The below image shows a composite of all three relevant frames with a threshold applied and mask to highlight the hidden numbers:
