What causes videos to start off black or glitchy on an AMD Radeon HD 6700?

This happens in Google Chrome 39.0.2171.13 beta-m and Firefox 32.0.3, it works fine in IE.

To me, this is the key. I wonder if this has to do with 3D acceleration mucking up video playback. Meaning, modern browsers such as Chrome, Safari and FireFox have hardware acceleration of page content set as a default.

The way it works is—for all intents and purposes—the browser window is treated as one, flat side of a 3D object. The browser pushes all of it’s rendered content through the video card driver and it displays on the screen. If all goes well, the content looks exactly the same as what happens when the image is rendered directly through the system, but it should render a bit faster on more complex pages.

I would poke through the Chrome and Firefox settings to see if you can disable video acceleration. Perhaps even in the driver itself? Now that would at least get the video to display properly in your browser, but the deeper issue of why they are not playing nice is still in play. That I’m not clear on, but it could simply be a driver issue or even a driver preferences issue. Maybe dig into the system and see if you can trash the driver settings to force it to create a new file?

To answer why you see glitched black frame,

Video files are not just consecutive images (like for example GIF format), they have various ways of compression. Here is a cool video explaining the compression taking place here (the explanation is ~first 3 minutes of the video). For some reason the browser doesn't load the first image in the video clip properly, instead just shows a black screen, so you get that black glitch. If you immediately skip to the begging or just wait until the entire scene has changed, the bug will disappear because the player was forced to load an entire image.

Hey everybody i had the same problem. what fixed for me is go to new tab type chrome://flags and search GPU rasterization MSAA sample count i had it on 0,set it to 16 and the problems are magically fixed. (i have GTX980Ti) let me know if it worked. turning off Hardware accerlation completely works aswell but some demanding things start to lag if you dont have very powerful cpu (ex:6K60fps video)