I see this kind of video crop up on YouTube every now and then, and I quite enjoy watching them as I find them quite humbling and reminiscent of a bygone era, etc. etc. but I can't quite put my finger on the following.
In the following video, as an example:
What is the cause of the distortion from approximately 1:08 to 1:22? I remember hearing similar horrible noises from VHS videos of marching bands that I used to play in during the early 2000s, but attributed it at the time to other people watching wanting to have the volume up to 111 (yes, one hundred and eleven as the TVs at the time invariably went to 100 and 101 wouldn't be loud enough).
The recording in the YouTube video I mentioned above seems quite midrange heavy during the speech, but it's particularly prominent during the orchestral piece between these times (1:08 to 1:22 or so). This seems to follow along with similar recordings from the era and country - a very distinctive, distorted "o" sound, for example, in speech.
I've had a look in Audacity and I can see that it is quite low midrange-rich, 150 to 350 Hz peaks at roughly double the rest, however what I really want to know is, why do these recordings typical of this era sound this way? The signal does not clip like you'd expect of a poorly recorded recording (i.e. recorded from original media into a computer with an ADC going into saturation).
Also, interestingly, without an audio FFT tool such as Audacity, I would have said that the predominant peaks were much higher in frequency, nearer the 1 kHz mark.