If you are having this issue there are a couple of things to try which should hopefully fix it.
1. Try a different browser - we know the livestream is working well in chrome, firefox and safari
2. If you are already using one of those browsers please check you have the most up to date version
3. Make sure you have the most recent version of flash player installed. You can get the latest version at: https://get.adobe.com/flashplayer/
Once you have done this hopefully your issue will be resolved!