Computer graphics exhibit certain artifacts when converted to NTSC video.
Video is an analog format, while a computer graphic uses discrete pixels.
The edges of each object in a computer image are inherently abrupt. The transition from one pixel to the adjacent pixel is a digital, discrete change in value, represented on a video oscilloscope as a square wave. Such rapid transitions exacerbate NTSC footprint artifacts such as dot-crawl, ghosting, and ringing. Also, any single-pixel lines or images exhibit flicker as they only appear in one of the NTSC fields, and not both. Flash frame rates need to be multiplied an odd, fractional amount to maintain the author's original frame rates while displaying 29.97 frames per second on video.