I wonder if it could be added to an existing video file in a way that appears to be just noise.

> The current solution works 99% of the time and only rarely encounters errors in practice. It works 100% of the time under ideal conditions (i.e. when not round-tripped through Youtube).

> When encoding some data, each byte is converted to a "tile", which is a rectangle of arbitrary size filled with one of 256 colors. The "palette" used for these colors was specifically tuned to maximize resistance to Youtube's compression.

Sounds like you'd want to add an error correcting code on top?

See https://en.wikipedia.org/wiki/Error_correction_code

Seems vulnerable to barely perceptible palette shifting. Would be more interesting to use visual features that video codecs are optimized to preserve.