It can be done using Netflix with Firefox. There can be issues with Netflix and Chrome. That's because Google products use their location services and don't rely solely on IP. Don't know about the Win8.1 app since I typically use Firefox. If Netflix works with Firefox and not the app, it's an app issue.
One possible issue with modern operating systems is that the apps use O/S location services to determine region. Just using a proxy may not make any difference to the reported location. Disabling location services won't work either because apps often won't work unless they are enabled. The answer is to determine how to fool the O/S location services.
Some apps are region specific from the app store. Not sure if the Netflix app on Win8.1 is like this but it's possible. The way to get around this issue is to install the app using a proxy.
Can't say I like the sound when using browsers either. Surround sound is not completely lost but pro logic on a PCM stream is not as good as DD5.1 or DD+. If the sound is an issue, I use a Chromecast. That's a Google device though. Never tried it with a proxy service but I'd expect location services issues since I have experienced them with Chrome.