Spray vs Liquid Seafoam.
Just did this myself. Bought the 2 pack that had one of the aerosol cans with the little red straw and a regular can of seafoam. Did the straw first exactly as Tim did in his video; measured the distance from the plates and all. Took about 5 minutes to do with the better half holding rpms at 1500ish. Let it sit, went to start it, and there was no smoke or anything. Idle hadn't changed, engine vibrations felt the same, etc. I was elated first, meant it was clean and the PO took better care of it than most. Then I got to googling... A lot of people had this issue.
Fast forward a few hours and I decided to do it through the PCV hose using 1/3rd of the regular Seafoam. Ill admit that I was very timid after reading about hydro-lock, but I sucked it up and just went for it.
Using a 2/3rds measuring cup (close enough to 1/3rd of the can) I poured the Seafoam into a small Mason jar. I started the engine and pulled the hose, placing it with one hand at the lip of the jar. The other hand tilted the jar just enough to make Seafoam flow towards the suction. After about a minute I was done and left it alone for about 30 minutes. Started her up and poof, white smoke everywhere!
I'm not sure the spray DIDN'T work, but I know the liquid worked far better.