The present disclosures relates generally to digital watermarking and data hiding. One claim recites a method comprising: obtaining data representing video; using one or more programmed electronic processors, embedding a first watermark signal in a first portion of the data, the first watermark signal comprising a first signal polarity; using one or more electronic processors, embedding a second watermark signal in a second portion of the data, the second watermark signal comprising a second signal polarity that is inversely related to the first signal polarity; rendering the watermarked video in real time, in which due to temporal averaging of the first watermark signal and second watermark signal over time, the first watermark signal and the second watermark signal are hidden from a human observer of the video. Of course, other claims are provided too.