I'm not an expert too but AFAIK ferrofluids are actually attracted by magnets. The spikes are probably as a result of having string and weak locations of magnetic field and the the liquid rushing into those.

But yes, Maybe I'm interpreting the video wrongly. Yet, to me it looks like the bulky part of the sample is being repelled by both poles of the magnet as it stands upright with the pointy end at the bottom each time. IMHO if this was due to attraction, the pointy end would be at the top.