Vent Pipe Video

I am struggling with a leak that I have now removed drywall from the ceiling in my kitchen to only find that there is no "leak". With cold temps outside, my vent pipe is forming condensation and that is what is dripping down and onto the drywall causing it to crack. I crawled into the attic and there is insulation around the pipe on the attic floor, just like the entire attic. Any ideas on this one? I am stumped.

My kitchen smells like spoiled garbage. I live in Royal Oak Michigan and it is winter here now. What can I do to get rid of the stink? Seems to be coming from my kitchen sink and the cupboards directly near the sink. I tried using bleech and it worked for 1/2 a day, but then the stink came back. What is it? How can I fix it? Is my stink pipe perhaps clogged? If so, how can I check to find out? It sooo STINKS HELP Lillian