The author's comment there says "If you want to color the whole line even further than its contents, you need to use signs." That's important for avoiding this problem.
To make Vim work like tail -f, run one of these: (more explanation)
:set autoread | au CursorHold * checktime | set updatetime=1000 | call feedkeys("lh")
:set autoread | au CursorHold * checktime | set updatetime=1000 | call feedkeys("G")(this one constantly scrolls to the bottom, which can actually be irritating unless it's something that's easy to toggle on/off)
To automatically fold the loooooong Java stack traces, run :set foldmethod=indent
