My daily driver is a Mazdaspeed 3 with a direct Injection 2.3L. Like many other early Direct injection engines, my intake valves have to be cleaned about every 40k miles. This process looks like this:
1) Remove intake manifold
2) fill closed intake ports with solvent and let them soak for about 15 minutes (to soften the gook that builds on them)
3) remove solvent and media blast it with walnut shells
4) rotate the engine so the other intake valves close and repeat
It is a SUPER MESSY time intensive job. Why do I bring it up?
The first time I did it (I have cleaned them 4 times now), I put Seafoam in one port, Gasoline in another, diesel in another, and Techron Fuel injector cleaner in the fourth. Of all these cleaners, SeaFoam was the least effective at softening/removing the gook, followed by gasoline, then diesel. Techron was pretty amazing but at $10/bottle, too much $$. I use gasoline now.
Also, I rebuilt the 401 in my jeep twice in 2 years (long story). First time it got brand new pistons. The second time was after about 5k miles and the top of those new pistons were coated in gook. Again, decided to try different solvents. SeaFoam, alcohol, paint thinner, carb cleaner, engine degreaser, gasoline, and some other juices I had on my self but I don't remember. Seafoam was not the worst of them but it was definitely worse than most. Carb cleaner was the best (by far).
Personally, I think if you want to clean your fuel system: Techron. If you want to clean your crankcase: Half a quart of ATF with your oil. If you want to clean your intake track: Carb and choke cleaner. All of those are cheaper and more effective IMHO. All that white smoke is burning Seafoam, not contaminates. You pour Seafoam in a brand new engine and it smokes the same as an old crusty 2.9L with 160k miles.
BTW, Project Farm is one of the only youtube channels I subscribed to. I love that guy. No shade on the video, either.