In most cases, either updating to the newest video drivers or disabling hardware acceleration will resolve this bug. In addition, please see this FAQ:
In an attempt to consolidate numerous threads about video problems with Flash Player 18.104.22.168 I've created a new post where I'd like to have people who are still encountering this issue to either post or link to an existing post with their information.
We're asking for 4 pieces of information
1. A brief explanation of the problem
2. Did disabling hardware acceleration fix the issue
3. A sample URL
4. A copy of your dxdiag report
If you've already provided all 4 answers to us, thank you and please take a minute and copy the URL of your post (right click on the highlighted title of your post as shown in the example screenshot below) and paste it as a reply so your input is not lost.
If you haven't provided these answers, we ask that you take a few minutes and create a new post with the required information.