Quite the light burst we have here. If it did not come from a 'physical' source, then it comes down to it being any number of things. Aliens / ufos (landing, taking off, or abducting, etc), energy beings, bleed-over from another frequency where maybe an 'experiment' of sorts was going on, etc, etc. There are many possibilities for what occurred on that newscast. I'm not saying it was an occurrence that is not of our physical world, but what I am saying, is that we need to look beyond sometimes.
Although it looks like an 'explosion', it doesn't look like a 'normal' explosion to me. While I can't say what it is, I can say that it is out of the ordinary to have something like this caught on film, and live television at that.