I created two demos in 1986 that also show additional colors to the basic palette of the C64. I don't recall whether these demos used a pattern of pixels that caused "CRT bleed" [1] or whether colors were quickly alternated in the way described by the article.
I just ran the demos in Vice and took screenshots [2]. As an aside, notice that the sprites extend outside the regular border which was long considered impossible on the C64. A whole arms race started between demo groups to beat each other by taking border sprites to the next level. I contributed to a number of those demos too [3].
[1] Of course, I just ran the emulator on a non-CRT display on MBP but I don't know how well the C64 emulator also emulates the bad video quality of 80s TVs/monitors. I seem to notice some bleed artifacts in the screenshots.