I saw the missile from S.F. area and what’s seen on the video is not an explosion. The missile fuel is continuing to burn as a small point and the trailing exhaust smoke is aglow from the intense brightness of the engine. Perspective as the missile is tracking away and climbing, and accelerating can mislead an unexpecting observer. The missile is doing something most of us have never seen, climbing AND accelerating to somewhere just beyond the speed of stink! It’s an amazing sight to see.
Do not confuse and dismay the "true believers". They are convinced they saw an explosion, where anyone that has seen a missile launch at dusk knows how strange the exhaust plume gets when the missile exits the atmosphere.
Just think at the panic if it had been earlier in the afternoon so the smoke trail would have been visible and had high altitude winds to twist it all about! The UFO and other theories would never quit.
I had the pleasure of living in Ventura county and being on the Vandenburg launch listserv so I had a tip for all the upcoming launches. Some were quite memorable, many like this, classified so you only saw them as they happened.