Slow scan television is a method of sending and receiving images over radio. It is not a means of sending full motion video, as each image takes anywhere from a few seconds to a few minutes to transfer, depending on the mode. Slow scan television (SSTV) works over any frequencies and equipment usable for voice, including AM and SSB on HF frequencies, and narrow-band FM on VHF and UHF frequencies.
Slow scan television was originally developed using an analog scan converter and modified video camera, with output on a CRT with ultra-high-persistence phosphor. Later, solid-state scan converters were developed which allowed the use of standard video equipment for image input and display. One of the more popular scan converters was the ROBOT.
Modern SSTV transmission and reception is usually done using DSP-based equipment or a personal computer. Software is available for SSTV using your computer's sound card and software routines to encode and decode the image data. A simple audio connection to your radio's microphone and audio out terminals are the only special hardware needed in this case. Some SSTV programs include W95SSTV and ChromaPix for Windows, and QSSTV for Linux.
There is also some rather cool SSTV hardware now, notably, the Kenwood VC-H1 Visual Communicator, a small integrated digital camera, color LCD display, and scan converter all built into one small handheld package, ready to plug into a handheld radio. James Bond WISHES he had one of these babies.
Pedro's writeup actually refers to ATV, amateur fast-scan television. This allows standard NTSC (or other format?) video to be sent over amateur frequencies, with allocations present in the bandplans for ATV in the 70 centimeter, 33 centimeter, and 23 centimeter bands. You can receive ATV signals on 70 centimeters without any special equipment; simply attach a cable-ready television to an antenna, and set it to cable channel 58 or 59. ATV signals are likely to be much weaker than broadcast television signals, and are usually sent and received using directional antennas.