Yeah, but what's the criteria for 'product' placement. For instance, I wouldn't categorise a video of the MkI empeg as product placement. It is not representative of anything that the company sells today which I think is an important distinction.
Basically you're trying to avoid subliminal advertising of any companies products, and also avoid defaming any products. So having a video containing a 5 year non-descript sedan in reasonable condition for it's age is ok, even if it's obvious to most people that it's a Ford Escort. But having a brand spanking new top-of-the-line Escort being shown as a luxurious, sporty and exciting ride in all it's shiny glory (!!) is not ok. Neither would portraying an Escort as a heap of [censored] be acceptable. (Which IMHO, it is...I have a rental escort at the moment with only 11000 miles on the clock, and the engine and suspension both sound fscked. Still beats the Neon I had before though).

At the other end of the scale, you could consider that fence posts are products. As are many crops.