The cameraman would not be able to film the explosion. Either the pyroclastic storm or the electromagnetic pulse would render the camera unusable, and at least erase the magnetic tape in the camera.
When the RBS newsroom transfers to their reporter Megan Barclay in Charleston, she begins her report saying; "The situation began approximately 1 hour ago". The report then screens some video from their reporting team and then shows some Super-8 footage which was filmed by a tourist on a sightseeing boat. Super-8 is a film, not video, format. Normally the cost of the film cartridge included postage to a Kodak laboratory where it would be developed and then mailed back to the owner. In this instance, After the boat had reached shore, it would have been necessary to take the film to a Kodak developing facility to be processed, after which it could be taken to the news studio. Due to the time required to get the film to a laboratory for processing and then to get to the news studio it would have been impossible to do this within the time allowed.