1. Before installing the most recent version of Adobe Flash player, you will need to first uninstall any older versions of the Flash player you've installed in the past and currently have running on your computer.

Please completely uninstall the version of Flash you're currently running, before upgrading to the most recent version. To uninstall Flash, follow Adobe's instructions, listed here. You'll need to download Adobe's official Uninstaller to remove Flash.

2. Once you've uninstalled the older version of Flash, you'll be ready to upgrade to the most recent version of Flash.
To upgrade to the most recent version of the Flash player, please follow these steps:

1. Follow Adobe's instructions for reinstalling the most recent version of Flash.

2. Once you've downloaded the latest version of Adobe Flash, please exit your browser.
3. Finally, click to install the update that you just downloaded to your computer from the Adobe Flash site.
Once you've done so, open your browser again and go to YouTube. You should now be able so successfully watch videos!

The only problem here is that when hundreds of millions of people are asked to upgrade their Adobe Flash Player, and then those hundreds of millions of people go to Adobe to do the upgrade, the Adobe Flash Player Upgrade site crashes.