Bleed valve.

[Kiss4aFrog]

Is the noise something new ??

I don't now about the video.

+1 on the spider gasket. Easy enough to put the handle between positions, pull the five or six screws and inspect it. I'd have some silicone plumbers grease on hand if you do pull the cover to lube it up when it goes back together.

I used to use Vaseline but was told the petroleum can damage the rubber !!

 

[bobodaclown]

another thing to do to see if it's sucking in air is to run a steady stream of water over the multiposition valve and see if the gurgling/air sucking goes away, but it's on the pressure side/after the pump so... sucking air before the pump? run water over the connectors see if the air in the basket goes away. You could also you foaming type shaving cream, see if it gets sucked in.

 

[mkdsk101]

You might have something there bobodaclown because my collar wrench broke and I had to hand tighten the multi position valve.

 

[bobodaclown]

Here's the manual in case you've lost it:
http://www.waterwayplastics.com/manuals/810-0118.0209.pdf