Which of the following is required to view videos stored on a DVD?

To view videos stored on a DVD, you need an optical drive. Optical drives are hardware devices capable of reading (and sometimes writing) data from optical discs like CDs, DVDs, and Blu-ray discs. These drives use a laser light to read the data encoded on the discs. For viewing DVD videos, the optical drive must support DVD media, which it decodes and sends to the computer for playback.

References: The use of optical drives for reading DVDs is commonly found in resources like the CompTIA IT Fundamentals exam guide, where they explain the functionality and necessity of different types of drives in computer systems.