I'm trying to figure out how to fish this thing. Here is Tackle Warehouse's description:

"Invented by Jackall Japan and now available in the States, the Jackall Seira Minnow 80S is part of Jackall's I-Motion series. A popular technique in Japan, I-Motion basically means the lure swims in a perfectly straight line, like a minnow would that is not being threatened. Said to attract bass that are looking for an easy meal from unsuspecting prey, the Seira Minnow features several innovations that allow it to stay balanced and track perfectly straight.

A specially cut hole in the bait's mouth funnels water out slits in the bait's gills, helping to stabilize the bait and provide added realism, while an advanced weight transfer system locks the bearing in place during the retrieve, but still allows it to transfer to the tail for extra long casts. Even the custom designed, glued feather tail helps keep the bait stable, functioning almost as a rudder. Available in several proven colors, the Jackall Seira Minnow offers another innovative way to get those finicky and pressured fish to bite."

It looks like a jerbait, but I would think that jerking on it would defeat the purpose. So... do you fish this like a jerbait or more like a crankbait or what? Any ideas?

By that desription, it sounds like it would be fished like a crankbait.  Cast it out and use a steady retrieve on the way back with maybe a few pauses.  Retrieving like a jerk bait would defeat the purpose of what the lure is intended for.  JMO.

In addition to what's on the video I remember reading that they fish this on very light line.

Ifr you've ever fly fished with a streamer fly, the streamer has the same kind of action, just a straight retrieve, no wiggle and bass will hit streamers.