Depending on what version of tvh you're running (I simply can't remember the old version, I'm afraid), there should be a Watch TV button in the top-right of the EPG tab. If you press that, it will launch the VLC plugin and allow you to select a channel.
You can also list the channels in the Configuration screen and launch a specific channel from there. Again, it needs the VLC plugin to work.
Having said all that, when I've tried in the past I've had various problems on various browsers. So, I just tested on my Win8 PC, and noticed:
1. Full-screen Chrome just gives up - presumably, some problem in handing over the stream to VLC, or running the plugin fullscreen, and
2. Internet Explorer won't even open all of the WebUI tabs, complaining in the JS Console about various errors that the other browsers don't mind, and
3. Firefox works, but I have problems processing the MIME type. If I just click "play", it tries to download the stream, which - of course - takes forever. However, if I copy the Play hyperlink and paste in into VLC as Media / Open Network Stream than it works okay. So it's a config issue on my PC, which isn't helping you...!
I only ever watch live TV streaming into XBMC, though, so I've never really tried these.