Works fine in FireFox 28 and Safari 7.0.2 (both the current versions of these browsers) on Mac OS X 10.9 here.
The black looks like it is a bandwidth issue. It looked like a black head in FireFox for a few seconds, but then (I guess when additional data was downloaded) it looked similar to what Safari showed. FireFox is a bit darker and seems a tiny tad slower.
The black looks like it is a bandwidth issue. It looked like a black head in FireFox for a few seconds, but then (I guess when additional data was downloaded) it looked similar to what Safari showed. FireFox is a bit darker and seems a tiny tad slower.