I was watching “Chicago Tonight” on WTTW last night and they were showing video clips from previous presidential debates. The quality of the video and audio was not very good, even in clips from the 90s. Have the cameras and recording media improved since then, or is it that the tapes deteriorate over time?
Both.
I’ve been told by people who work with video archives that one of their big problems is maintaining a working set of tape machines to read all of the old sizes and formats of video tape. There has been a tremendous amount of technical evolution since the first video tape recorders were introduced.
Most of the old shows on TV were shot on film. Those still look good today. Before video hardware became portable, a lot of news footage was captured on 16mm film.
Way back when, in the early-mid 80’s, the TV station I was with used U-Matic tapes. A home-grade VCR that you can buy today for $60 has better performance than U-Matic did back then. And that U-Matic *tape * would have cost you $60 on its own.
Of course, at that time, U-Matic performed better than home VHS, so the cycle continues. 
Aside from advancements in performance of the tape and recorders, video tape deteriorates with time.
Some folks say “print-through” is a problem, some say it’s not. Basically, it’s the magnetic pattern transferring to adjacent layers of tape on the reel. This is unlikely to cause an actual ghost image, but more likely would show up as static. I have heard print-through on audio tapes - it appears as a pre- or post-echo, but is generally so faint to be inadible except during silent passages.
More commonly, the adhesive holding the magnetic particles to the tape deteriorates, and the particles simple come loose and fall off, taking the information with them.