as hot as the surface of the sun
Yeah, they like to claim self-contradicting things like this:
HHO produces a 279 degree flame, that can sublimate tungsten in seconds at over 10,000 degrees.
If this were really sublimating tungsten (boiling point of 5555 °C = 10031 °F), then yes, it would be hotter than the surface of the sun (5780 K = 9940 °F). But it's not true. Whenever you see them demonstrating this feat, they're aiming the torch at tungsten rods in air.
Tungsten doesn't sublimate in air. It burns, reacting with atmospheric oxygen to form tungsten trioxide, which then melts (at 1473 °C) or vaporizes (1700 °C) and is blown away by the torch, exposing a layer of fresh tungsten, which burns, etc.:
When a tungsten specimen is heated, its surface becomes covered with crystals which melt when the melting point of tungsten trioxide is reached, the liquid oxide flowing to the lower (frontal) part of the specimen and forming a drop which then separates. Melting of the oxide coating is accompanied by rapid self-heating of the specimen with transition to the combustion regime. - Ignition and combustion of high-melting metals (tungsten, molybdenum, boron)
The particles that are blown away form smoke, which you can see in the video.
This is why light bulbs are bulbs, and not just tungsten filaments hanging around in the air. They need to be surrounded by an oxygen-free atmosphere in order to take advantage of their high boiling point. When the bulb breaks, they burn up.
"HHO gas" doesn't exist. It's just a hoax name for conventional oxyhydrogen gas (2× H2 gas mixed with 1× O2 gas), as produced by a conventional "water torch" or "water welder", which burns at 2800 °C, plenty hot to turn tungsten into smoke. All their other claims are equally sloppy and unscientific.