In the past few weeks I have been really getting into these guys. They have some truly amazing stuff but they're one of those bands that you really can't get a good grip on by watching a YouTube video, you need to listen to a whole album.
As far as some of the comments in this thread go: FL are associated with jazz because they started off as a jazz/punk band and one of the founding members was Chicago free jazz sax and trumpet player Hal Russell. He was in his 60s at the time—pretty cool old guy! I'm not sure where the black metal comparisons are coming from, I don't hear it personally.
Anyway, even though I just warned against judging them by YouTube videos, here's a little bit of studio material from them since everything else in this thread seems to be low quality live recordings (and maybe Jackhammer will take note of the underlying musical dexterity and give them a second chance
):