When I got my filter, I freaked out because my Betta was being blown everywhere, and then sucked up by the filter. And he had NO clue what this evil thing was.
I searched the net, and found the other article (that someone linked to here), and that method worked very well. I also put a sponge-like cloth thing inside of the stretched bottle, and placed a piece in the intake tube.
My Betta was really curious, and bit at it, and tried to go into/underneath it, but I rounded the edges, and the sponge thing was there.
I played around with different methods for a few days, and now I just place a sponge in the outflow, and in the intake. Just like Lion Mom shows, but I didn't require the rubber band, it just stayed. The water is practically still, and the tank is still being filtered well.
Every now and then, I take off the baffle because my Betta LOVES to swim against the current, eat the bubbles, and just check out the filter (Silly fish!).
As long as he's happy, I'm happy.