Firefox and Opera use two different plugin types. Firefox uses NPAPI and Opera uses PPAPI. To install for both browsers, do the following:
- Launch browser (e.g. Firefox)
- Navigate to https://get.adobe.com/flashplayer
- Download NPAPI installer (the page auto detects the OS and browser to offer the correct plugin for the combination)
- Repeat 1 - 3 with the other browser.
- After downloading the installers, navigate to the location they were saved to and launch the installer
- only one installer can be executed at at time
That is completely unhelpful. Because two flash plugins working at the same time crash videodriver.
Sorry, I missed the last part of your comment.
Please see the Video playback issues tech note. Follow the relevant troubleshooting steps. If the issue persists follow the instructions in the 'Submit your problem report to Adobe' section to file a bug report, and include all of the requested information.