In episode 4 of the George Knapp Netflix show "Investigation Aliens", a light is shown descending into the water
I don't know the show. If it has a similar approach to evidence as the
Skinwalker Ranch franchise shows, I'm not sure debunking
Investigation Aliens content will achieve much. My impression is that SWR-type shows are chasing ratings, they're not trying to establish the truth or advance our understanding. Like similar ghost hunting series,
wherever they go, they
will find "anomalous evidence".
The OP video appears to show a light above water gradually descending until it is either just above, or possibly beneath, water.
We've had waterproof lights for decades. Some are cheap. And it's easy to improvise a temporarily waterproof covering/ container for an electric torch/ lamp etc. if it's not being used at any great depth (though only ever use appropriately tested waterproof items for serious applications!)
(1)
@NorCal Dave and
@john.phil have demonstrated that illuminated fishing lures are a thing, as are illuminated angling floats.
(2) Such lights can be lowered into the water, and retrieved again.
(3) An off-the-peg drone could carry a small waterproofed lightsource on the end of a tether.
We might ask why anyone would bother, but the fact is people
have put effort into UFO hoaxes. AFAIK, many alleged hoaxers are (or claim to be) believers in UFOs, not sceptics or Govt. agents /other authority figures/ fashionable bogeymen.
(4)
Investigation Aliens is probably aimed at UFO believers and the less critical viewing public, not at astrophysicists/ oceanographers/ biologists/ the defense community.
(5) I predict that most episodes, the cast will find some mystery that they cannot explain except as possible evidence of alien visitation. Not because they've found testable evidence of alien visitation,
but because that is the format of the show.
George Knapp is just doing his job, earning a crust.
And because of that, whatever he actually believes on the subject, he's not going to be on
Investigation Aliens saying
"But this is ridiculous! That could just be a fishing lure or LED torch in a condom, on the end of a fishing line!"