This article is from the CD-Recordable FAQ, by Andy McFadden (firstname.lastname@example.org) with numerous contributions by others.
Short answer: you don't, unless you have a CD-i add-on board. Even if you
have a CD reader compatible with the CD-i (Green Book) standard, there are
still a number of obstacles in your way. The filesystem used isn't
ISO-9660, and CD-i players are based around a 680x0 CPU and have special
hardware for video and audio.
Longer answer: it depends on what kind of disc it is, and what you mean
PhotoCD and VideoCD discs are CD-ROM/XA "Bridge Format" discs that play on
CD-i players as well as dedicated players and computers. These use the
ISO-9660 file system, and can be read with commonly available PhotoCD
software and MPEG-1 players.
DigitalVideo discs from Philips manufactured before June, 1994 are in CD-i
format, not VideoCD format. If your CD-ROM drive supports raw 2352-byte
sector reads, it's possible to pull tracks off of a Green Book format disc,
and extract audio or MPEG video data. You can get a CD-i filesystem
for Windows from http://www.icdia.org/articles/filesystem.html.
VCD PowerPlayer from CyberLink (http://www.cyberlink.com.tw/) can play
CD-i movies directly off of a Green Book disc.
In-depth information is available from http://www.icdia.org/.