In short, the legality of watching US Netflix in another country depends on how you do it. Gaining access to Netflix libraries in other countries falls somewhere within the grey area. However, Netflix typically manages what you can and cannot watch based on location. While technically, it's perfectly legal to stream content from the US when traveling to another country since you've paid for your Netflix subscription, Netflix maintains motion picture license rights by controlling what you can watch. Furthermore, Netflix has been forced to crack down on subscribers using VPNs and other methods so that they keep these third parties happy. This situation may be one reason why Netflix has focused more and more on original content and less on film and TV produced by outside sources. Regardless, it's still morally dubious to deliberately get access to more content than you're strictly allowed, even when traveling. It's not as legally questionable as something like Kodi, but Netflix is taking VPNs seriously and has begun blocking some of the most popular VPN services.