Just thought I would try the App on the Windows Store for Now Tv.
I have to say that it works very well. No streaming issues and excellent picture quality. Sadly if you are stuck on Windows 7, then its a no go.
Welcome to the forum. The NOW TV Player helper app should work on Windows 7. Have a read of the following help article
You may need to install or reinstall the Player, you can do that from here
Is your sound in sync with the app? I had to stop using it because of a very noticable delay. I found that watching via Internet explorer, which uses silverlight, was just fine. Now IE forces me to use the app, like Firefox has been doing for a while now. Don't think it's anything to do with my hardware I've got a £100 Soundblaster card in.