I work in the UI development space at Netflix, and I certainly wouldn't describe it as anything remotely close to a culture of fear. Only two people on my team in the past 3+ years have gotten let go, any they were both gross under-performers with poor attitudes.
As far as "A players", it's not just a matter of hiring people who are good at their jobs, but also A-players from a team and interpersonal perspective. I like everyone I work with because very few people have strong or confrontational personalities. At the same time I know the people I work with are honest with me, and I feel free to be honest with them. If I mess up, I don't feel like it would be in my best interest to try and hide it or make excuses; I own up to it, and am still around after so many years. I've also never witnessed any sort of team-v-team competition.
The visa issue is not something I've encountered, either. Not to say there aren't a number of H-1 workers -- and those tend to be exceptional talents -- but my team for example has hired around 15 people devs and testers in the past 6 months, and all of them are local talent.
I realize this reads rosy, and some teams in the company may have different experiences, but I honestly would never leave here willingly. Keep in mind the glassdoor rating includes a lot of complains from customer service workers who were let go, and as with most internet ratings, the people who post reviews are most likely the people who are pissed off.