Video channels

There are a few YouTube channels with APL as a main subject:
 * DyalogLtd
 * DyalogUsermeeting
 * rikedyp
 * Rodrigo's APL Corner
 * code_report
 * yernab
 * Jamie Raymond
 * Mi Lia
 * Adám's APL
 * APLtrainer
 * Aaron Hsu: Co-dfns
 * Jeremy Howard: APL Study Group