Mass Effect Andromeda Multiplayer Beta (cancelled)

First, it depends on if this is a beta or a demo.

A beta implies unfinished game but approaching finished status) and the developer is seeking feedback from a selected group of people to tell them bugs found, things that seem weird/need improvement, suggestions for making the game better, and stuff like that. Stuff they can either tweak before the game launches, or build into a patch that will come out later, or ignore entirely. Generally, players submit this feedback through a private/secret forum or using survey links provided by the developer. Helping with a beta like that is just what it sounds like - helping to identify issues and submit feedback. It is not a party for you to bring your friends into/take video/share with the world UNLESS the developer says that's okay. More often than not, it is NOT okay and you have to sign an NDA and then risk legal action from them if you proceed to break that NDA and tell the forum all the pretty shiny things you saw in the beta. A beta isn't for hype - a beta is to try and do your part to assist the devs with making the game as good as possible at launch. It doesn't make you a BioWare (or any other game company) employee, but you should approach it with that manner and seriousness.

If it's a demo, that's generally a game that's about ready to release and the point of the demo is to be public and raise hype, while also possibly doing a stress test of how the game handles an influx of people suddenly playing it. Those don't require NDAs and you can share all the information your heart desires.