This is terrible tosh. You won't find any serious physicist saying things like this.
The writer confuses matter with mass for a start. That's the same category error as the one I was referirng to. Mass is, again, a property of matter, an attribute, not an entity. You can't have a jug of mass. You can have a jug of something that has mass. Quite different.
And then he goes on to talk bilge about mass being frozen light. Light has energy (not is, please note, has) and yes, if you annihilate, say an electron by reacting it with a positron, you get a burst of radiation (call it light if you like, though I think it is generally γ-rays). But light is not energy, any more than mass is. Light is a travelling disturbance in the electromagnetic field that has energy, as one of its properties. Light has other properties too of course, frequency, momentum and spin. The physical entity is the disturbance in the field and energy is one of its attributes. Rest mass implies energy, according to Einstein's formula, but that energy does not have to be radiation energy. If you charge up a torch battery you increase its chemical energy and its mass also increases (though not enough to be detectable). So it is not "frozen light".