yep. don’t know what youtube video you saw, but look at the link that @wesleyjames posted above.
not necessarily, although an insulated vent hose would likely cut down on noise.
I imagine that it would, to a point, but shouldn’t be an issue if your total vent run is still in spec with GF recommendations.
I used aluminum tape on the inside and outside of one end of the flexi hose to make it more rigid, then added a sort of interior gasket using adhesive-backed foam automotive weather-stripping, to avoid a gap around the wire. I also ditch the pinch-locks for a worm-gear hose clamp. I don’t tape the vent to the machine.
My exhaust has to exit through a roof vent, about 18 feet up, so my setup goes beyond the recommended specs. I use the original included hose (mine was a dead-standard dryer hose made by GE) for the first part of the run, so I roll my gf cart away from the wall for pro slot/fan-cleaning access. Then I go into an adjustable rigid 90 then into smooth-walled aluminum ducting up though the drop ceiling to an inverted y-junction that is capped & taped on the bottom as a cleanout/water-trap, and then taped into an external exhaust fan (which it-self is taped on every seam, bolt, rivet) and finally out though the ceiling an old bathroom fan vent. The old bathroom vent was just sort of roughed into place (round peg in a big square hole) so I filled that void with doorframe expanding foam.
you can see that I taped a section of the flexi hose to shorten it before it goes into the rigid 90, and that it is taped solid from where it enters the 90 all the way up to after the 90 has connected to the straight line (which is also taped the length of the pinch seam). You can also see my fan controller.
and here is the pile of dust that the ribbed flexi-hose trapped in the last couple of weeks (low usage since xmas)
no pics from above the drop ceiling, sorry. Its creepy and gross up there.
I figure it’s better to eliminate the cause rather than battle the effect.