Cool video. How in the heck did they make it?

You're right, the ocean has been very calm, and I had the same question with regards to why so much seaweed should appear under such calm conditions. The jumu was often entangled in the seaweed, suggesting that it had not been floating, but perhaps it simply got caught in the seaweed on its trip in. Still, there was a disproportional amount of jumu in the seaweed compared to other driftwood, again suggesting that it was not floating.

I often find jumu at the mid-tide line. It rarely washes up to the reaches of a high tide.

I also noticed a lot of, or at least more than usual, sponge over the last few days. Sponge in this area is actually fairly rare, but there was quite a bit on the beach on Monday.

This makes me wonder if perhaps a lot of lanbao has perhaps appeared recently.