From personal experience in Vegas, most people use their phones discreetly on the rail or behind their chip stack (if in a cash game) with a pop socket or some other holder. Right now, it seems like an 'easier to ask for forgiveness, not permission' situation for vloggers. As long as you're not holding up the game or filming people's faces or other personally identifiable factors, using a phone with a privacy screen seems to work fine.
If you have more obvious filming equipment, like the GoPro you mentioned, you will most likely have to ask for permission from the poker room manager beforehand.
Fortunately, poker rooms are finally starting to understand the value that vloggers bring and are becoming more flexible with giving permission. For example, Hustler casino in LA just made an announcement that they are vlogger-friendly and will hand out media badges to those creating primarily poker content on their channels.