If you're using video files, suggest that you go on to YouTube and go to the
specific karaoke uploaders there like Vocal-Star and Easy Karaoke.
If you have the right software you can right-click on a playlist and copy the
URL into the program and have it downlooad thousands of files while you
sleep.
It won't be the specialised stuff like SBI and KV but it will help.
There also thousands of files available here on GLO on the main torrent site,
my torrents always include the word karaoke so searcjhing for that will be
a good start for you.