It's a dual Atom powered device so Netflix will have to help you determine if this tablet can do what you are asking. Again, it's not a fully powered PC so you may want to re-think the choice. It's closer to a netbook in power and while nice, can have issues like you noted.
I just picked up the Samsung ATIV 500 and have found these too annoying issues. When Netflix movies start streaming in HD, I get a lag between video and audio. This makes HD unwatchable. My Wifi is fine as I have no problems streaming on any other laptop in the house. I also have an issue of not being able to launch a video file directly into Windows Media Player. Instead of launching the file when I click the link, it asks me to save as. I have WMP as the default and added all the file extensions to play with WMP. I can't get this to work either. This is very frustrating. Anyone else experiencing similar issues? Can someone help with a solution if this is not simply a limitation for this device? This may be a deal breaker for me if a fix is not possible. Thanks a lot in advance.