By bizarre coincidence I watched that clip of the Shell tanker at a safety briefing at Eastham refinery a few days back.
What happens is: tanker drives onto forecourt [somewhere in Europe] but parks in the wrong place. The YouTube clip is then cut to leave out the driver moving the truck, but we saw the full vid and what was pointed out to us is that he hadn't turned the tanker's Master switch off and so was able to get back in and start up.
With the truck repositioned, the second guy climbs up on the tanker and starts inspecting the contents of the tanks (you can see him peering in as he goes along) - though why the tanks were already open is a mystery. When he gets to the front tank he can't see properly so he takes out his mobile phone and presses a button to get the backlight on. That's what ignites the vapour. Once he's been blown off the truck he rolls around, on fire, straight past the open end of the hose you can see on the ground. The Youtube clip stops here but what happens is that the pipe ignites briefly then goes out. The flame front travels back down the hose and ignites the underground tank, turning the hose into a flamethrower. About two seconds later the camera melts so the video ends...
Ref. the skateboarding nutters: my kid brother broke a leg earlier this year after some trick went wrong. He fell about 4 feet straight down and landed on his kneepads. Not a problem, except that he crossed his ankles and sat down on the back of his calves, snapping one leg over the other. Of course the other guys refused to believe he'd broken it until he rolled over and his foot stayed put. That was 3 weeks before his 40th birthday