Light appears in only one section of the stream?

My dad just got back from a cruise on the Celebrity ship "Reflection." He tells of lit laminar streams in their solarium, where the light appears in only a small section of the stream. He says the light would appear in different small sections of an otherwise clear laminar stream. These lights would move about, and the laminar streams would grow and shrink.

He says that the light was not projected from outside the stream, but I don't understand how it would be possible for light to appear mid stream. The way he describes it is pulses of light in the stream, but of course light moves too fast for us to see it pulse down a stream of water. (Right?)

He literally describes it as if it were a laser bolt from Star Wars, a distinct section of light with a sharp beginning and end. He said it would sometimes travel down the stream, and other times it would appear in different sections. I just don't see how that's possible, but my mom corroborates his story.

Usually my Google-Fu is pretty strong, and I can't find ANYTHING like what he describes. I even found a video of the water feature on the boat he was on, but he says the video doesn't show the effect he saw. Here's the video: youtube.com/watch?v=BYuBnQrVzs0

I asked him if the lights below the streams in the video could have been projecting into the stream to produce the effect he saw, and he seems pretty sure that this wasn't the case. Does anyone have any thoughts on this?

In some of the nozzles is there i small needel at the output. Because the stream is so clear you cant see it light up. Then whater comes out of the needle so tiny bobbles appears and you can see the light in these bobbles so if you pulse light and bobbles you can make it appear different places.

Like this https://www.youtube.com/watch?v=05VcA081uXA

If you then pulse the light too i think you can make it happend special places. But just a guess.