When light reflects from a compact disk some is diffracted or bent to the side. Each position in the spectrum corresponds to a wavelength of light. So each color in the spectrum is a human perception of a single wavelength of light. Transparent plastic filters absorb a wide range of frequencies of light and allow other frequencies to pass through. Yellow filters absorb blue and allow green and red to pass through.
Human eyes perceive the resulting sum of green and red as the color yellow.
The energy of the light absorbed by the filter, warms the filter. A DVD disk has a narrower track spacing than a compact disk. Try using a DVD in this exploration and compare the results. This exploration was developed by Paul Doherty at project RAFT where they have an infinite supply of compact disks.