theres plenty of advice. you dont really need tailored help, you just need to reflect on where you slow down. is it between cross and first pair? do you ever look ahead? are your PLLs slow? do you need to learn more OLLs? learn better algs? i havent seen the video btw.
practice SMOOTH solving. not fast or slow, smoooooth. you have to use decent lookahead to get good times. sub-30 avgs are perfectly possible with relatively slow smooth solving.
once you have your lookahead to the point that you can assess two pairs at once and decide on which to do first, and how, then you can EASILY get to sub 20.