On the topic of the dog, this is a really interesting one. I think at the heart of it is the issue of private vs public life and how we see personal rights and social responsibility in a social media landscape which has demolished the idea of a private sphere. As I understand it, he put the video on social media to share with his friends. However, the impression that you can do this is a false one, as it quickly became viral and instead of occupying a private space, it ended up being big news in a public sphere. Now, humour is nothing without context, as has been said before on this thread. However, in the context of a public arena it is quite a ghastly video. We don't know this guy, we don't know his girlfriend, we know precious little about the dog. But because people have come across this in a public space, they're treating it as material designed to be seen by a public audience. As a video made for that purpose it is gross, crass and unacceptable. As a video for a private audience, it could probably be seen as quite funny.
If I'm honest when this first came up in the news a while ago, I assumed it would lead to some animal rights intervention, hadn't thought it would get this far.