[Don't forget to hit "f" after you start your favorite music playlist]
alias nest_win='_(){ local disp="${3:-1}";local tmpdir=$(mktemp -d);local prog="${2:-chromium-browser --user-data-dir=${tmpdir} http://www.youtube.com}";local win="${1:-460x340}";[[ "${1}" =~ ^- ]]&&echo "Usage: nest_win <win_size[default=460x340> <program[default=chromium-browser> <display[default=:1.0]>"&&return 1;(Xephyr :${disp#:} -ac -screen ${win} &> /dev/null & ); DISPLAY=:${disp#:} ${prog};}; _'