Analogue video (e.g. television) interlacing did actually begin in the 1930s, a few years before the Hindenburg disaster. But the original disaster footage would have been shot on film (not interlaced of course), cut into newsreels and then converted to a television signal via telecine.
Supposedly the original newsreals still exist, preserved by the National Film Registry: https://en.wikipedia.org/wiki/Hindenburg_disaster_newsreel_f...