When using the Chrome browser by Google, HTML5 videos show a black screen, audio is working normally.
AMD Radeon video card, Windows 7, Google Chrome version 33.0.1750.146 m
The problem is caused by the hardware acceleration option (I am still not able to understand the details of the problem). As I read in a Google forum, you can partially resolve the problem by disabling the “use hardware acceleration” option. To do so, go to chrome://settings/, select “show advanced settings”, scroll to the bottom and deselect the use-hardware-acceleration option. The only problem is: once I have done this, the “full screen” mode does not work properly anymore. When you set a video to the full screen mode, it only takes a portion of the monitor on the left upper side of the screen. I suspected that the Catalyst software had something to do with this. Catalyst is a software by AMD that manages the drivers of your video card and set/reset the commutable graphic cards feature. So I started Catalyst, searched for Chrome in the “commutable graphic cards” view and set it to “energy saving” value. I am sorry if you cannot find the name of this options in your Catalyst interface: I’m trying to translate them from Italian to English and I am not sure about it (Unluckily I have an Italian version of Windows 7 and, sometimes, it stupidly install Italian localized software even if I do not want it). After that, everything returned to normality.
I struggled with this problem for quite some times. probably months. I got away with it because the vast majority of the videos on the Web (and on Youtube in particular) was embedded with the flash plugin, that continued to work fine. Once in a while I could stumble on a black-screen video and momentarily switch to Firefox to watch it. It was no big deal. But now it seems that Google decided to shift an awful lot of video from Flash to HTML5 (a good thing, in principle) and that made my Youtube experience unbearable. Then the usual syndrome kicked in: are you really trying to keep me away from HTML5 videos, Chrome? no way. this could well be the last thing that I do, but I will see that fucking cat video inside Chrome, in full screen mode.