That's the problem with many of those videos; they're not verifiable. Was it due to a random action, was it intentional? How mch was edited out and how many other combinations that didn't have an interesting result were skipped over? There's no way to know.
Sure, and that's what the scientific studies, which are increasing in frequency, are for. I mentioned at some point in this thread to someone else the largest study by UC San Diego, which has a few potential biases but overall seems pretty rigorous.
Most of the current supposed evidence behind the buttons as of now is anecdotal, but the sheer number of people who seem to be able to attest to at least
some success is certainly compelling enough to make it worthwhile for the scientific world to investigate these claims. And I for one think that's a really great thing, because not only is AAC itself a potential breakthrough in communication, it also opens the door for even more research into related areas of canine cognition.
And to address your other post regarding word combinations, I see very very few people attempting to claim that dogs can use buttons to simulate verbal language to the extent humans use it. However, even being able to conceptualize the idea of stringing together just 2 or 3 words to verbally express an idea is already
huge based on current consensus on how capable (or rather incapable) dogs are when it comes to language. That's the whole thing with the button pushing craze; it's not that we're suddenly figuring out
dogs can communicate, but rather that they may have some (limited) ability to
connect words together and create a combined idea through them. Many of us have already seen that in our own animals, but the fact that scientists are now seeing the potential is what's important.