If you're feeling a little old school (and some might say masochistic), you could so a similar crude parser with a perl oneliner. This would be more efficient compute wise, but it's a bit of an acquired taste readability wise:

$ perl -ne 'chomp; push @a, $1 if /^\s*-\s*(.*[^:\s])\s*$/; END{print join(",", @a), "\n"}' /tmp/foo.txt
Harry potter,Perfect Blue,Jurassic world,Jurassic Park,Jedi,Star wars,The clone wars,MCU,Gumball,Flapjack,Steven Universe,Stars vs. the forces of Evil,Wordgril,Flapjack

Here perl -n makes perl look at each line individually, chomp strips off the trailing newline, we match for /^\s*-\s*(.*[^:\s])\s*$/ (a string starting with a dash and ending with something not a colon) and append the content of the matching parenthesis to an implicitly declared array @a. Then we add an END{} block which will be executed after all lines are parsed, where we print the array joined on ,.