Cancer, as you did not specify which, and that leaves room to come up with a relatively quick and easy death. Same for AIDS - if we can pick and choose the secondary infection that does us in, that might be a good way to go, too.
Not very keen on being burned -being beaten to death is probably equally unpleasant, but you might get to fight back, if ineffectually, for a bit.
That said, if I had to chose my own unpleasant violent death, I'd go with "shredded by canister and left to die".
I'm not a flamethrower expert by any means either, but I too feel that it burns a bit quickly (when he's flaming into the air, I was kinda expecting "burning drops" to fall down), but then, I don't know what fuel they would've used historicaly, and what they could and could not use for this demonstrations.
I ignored the comments, but they seem like typcial youtube fare, I only read those on guitar videos, for the added hilarity. ;)
no truth - no justice
all false belief
blinded by morality
there shall be ... no peace