As a VERY experienced rider and former roadracer, I am very skeptical as to how fast that guy was actually going. Don't get me wrong, he was hauling, and one wrong move by either him or the other motorist and he's history. I have had my 02 GSXR-1000 going an "indicated" 185 mph and I can tell you that there is no way you can manuver that fast at that kind of speed.
By the looks of how fast he was going I would estimate that he was around 100 to 125 mph. Again, still fast but NOT almost 300kph. The guy seems to have a death wish for sure.
Over the years I have known a few guys that thought they were a combination of Evel Knievel and Kenny Roberts (yes I'm showing my age) and most of them are dead! Guys that do that kinda stuff don't last very long.