Thoughts on this housing adapter

This is an Aquatica 5d mkii housing

I installed the Aquatica fiber optic led trigger 

The housing plug seals the body via 2 o-rings

The first/top o-ring is what seals the housing

I don't understand what purpose the second o-ring serves

Anyways, so other housing plugs are more robust - in the sense that it's a 2 piece system

The plug that's inserted into the housing hole and a nut that secures the plug - the nut ensures a tight seal and prevents the plug from coming out and flooding the housing

The fiber optic adapter just seems like it'll allow a flood?

I mean, it shouldn't, right?

It was designed by Aquatica for use in their housings

They know better

But at the same time, it just seems flimsy

This clip I took illustrates all this:

https://youtu.be/XGLACoH7e38

Thank you

The tight seal is not provided by the nut -the water pressure provides the sealing force.  I would think the retaining o-rings on your fibre optic ports will be fine.  On Nauticam housing the accessory viewfinders are retained by o-rings and have a double o-ring seal to keep it water tight.

i expect you housing will be fine, though I would test it first either a dive empty or a vacuum test.  An o-ring seal is only as good as its last assembly.