Make vidsfrompage, etc. quieter

[Chris Warburton]

They produce a lot of noise, which it would be nice to lower. We can set
the DEBUG var if we want to see everything, after all.

Note that simple solutions, like using '2> >(grep -v '^#' >&2)' to
suppress the big x11vnc warning, ran into some difficulties, presumably
due to job control, etc. (using "$!" to get the previous command's PID
might cause complications if that command involved process substitution,
etc.)