Im not sure if this is related you your discussion, but i have been trying to do the exact same thing. After a new system and reinstalling ytfzf and my old configs from a month ago, nothing i do to video_pref="" in conf.sh does anything, nor does -f show me any format options. i just get back 0/0 when its searching for video formats. HOWEVER: adding video_pref="worst" to line 1329 changes my format at last. Im sure this is not ideal, but after spending a good hr on this, i am tired and this i settle for till I can come back and spend more time. Maybe its the conf.sh, so i renamed it, nope.