[live-demo] Problems during the creation of a bootable USB

[Hamish]

ps devs- minor point re. that wget line: "${FOO}" does not protect
from space chars etc in variable names like "$FOO" double quotes
do. The ${} is parsed at a different stage and only clutters
readability, and propagates the misconception & false expectation
of protection. So don't use it unless you need to (eg when you
have "${FOO}_bar").

tx,
Hamish