Is this a leak in my Common Drain Line? Need help figuring video out.

[Richard Welch]

Video clip of Common Drain Line in my Condo before and after opening bathtub drain to release water from bathtub at the 3 minute 40 seconds mark.

Clip recorded using a non commercial endoscopy camera with 3 LEDs at cameras tip.

Recording up to the 3 minute 40 second mark the drain was plugged as the tub was filled.




What are the white flecks or reflections seen at 3:40 and past which appear ONLY AFTER water was flowing through this drain line??? Appears to be somewhat below where my bathtub drain line joins the common drain line.

Condo unit TWO floors below is getting water intrusion when my tub shower is used. No water intrusion issues in the condo unit directly below/under my units bathtub.

IS THIS A LEAK?

View attachment TUB BEING FILLED-DRAIN OPENED AT 3 MIN AND 45 SEC MARK.mp4

 

[Geofd]

Kind of hard to see but I do see something,can you get an extendable inspection mirror itight be that there is a partial stoppage and until that line starts to fill up it leaks out, that's just a guess , if you can get pictures of your tub tile,and shower valve that may help