Protect yourself while browsing by enabling click to play
The most dangerous activity on the web is not opening unfamiliar email. It's not clicking an unsecured link on a page. It's not chatting. It's not even sharing files.

The most perilous action you can take in your browser is watching a video. Adobe's Flash browser plug-in for web videos is as ubiquitous as it is nefarious. Flash has become the medium of choice for malware purveyors. As Garrett Robinson reports in a July 13, 2015, article on the Freedom of the Press site, Adobe released three critical security patches for Flash in as many weeks.

Flash security has been a problem for years: the recent patches enforce what Robinson refers to as Adobe's "already abysmal security track record." Steve Jobs hated Flash. Facebook hates Flash. And with the rise of HTML 5 video, Flash is becoming more and more unnecessary. In fact, Wired's Brian Barrett goes so far as to state in a July 15, 2015, article that "Flash. Must. Die."

To prevent becoming victimized by malware delivered via a compromised Flash video, you can set your browser to run Flash only after you have explicitly allow it via the "click-to-play" feature. Robinson's post explains how to do so in Firefox and Chrome, and he links to a How-To Geek post that provides instructions for preventing Flash videos from playing automatically in Internet Explorer, Safari, and Opera.

(Note that the February 10, 2015, post "Browse better with these three essential freebies (plus one valuable cheapie)" recommends using the free NoScript plug-in for Flash, and AdBlock Plus for all browsers. Both programs protect against malicious scripts on web pages, albeit in very different ways.)
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Enable click-to-play in Firefox

1) Click the menu icon (three parallel lines) in the top-right corner of the main Firefox window and choose Add-ons, as shown in the image on the left.

2) Choose Plug-ins on the left side of the new tab that opens, and in the drop-down menu to the right of "Shockwave Flash," change the default setting of "Always activate" to "Ask to activate" (as indicated in the screen below). Finally, close the tab.
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Set Google Chrome to ask before playing Flash videos

1) Click the menu icon (three parallel lines) in the top-right corner of the main Chrome window and choose Settings. Alternatively, type "chrome://settings/search#privacy" (without the quotes) in the browser's address bar and press Enter.

2) Scroll to the bottom of the Settings window and select "Show advanced settings." Under Privacy, choose the "Content settings" button.

3) Scroll to the Plugins section and change the default setting of "Run all plugin content (recommended)" to "Let me choose when to run plug-in content." This enables Chrome's click-to-play feature. Finally, click Done at the bottom of the window.

How to play Flash videos selectively

After you enable click-to-play in Firefox and Chrome, the browsers will display an icon wherever Flash content would normally play on a web page. To run the content in Chrome, Ctrl-click the icon and choose Run This Plugin.

The jigsaw-puzzle icon also appears on the right side of the address bar. Choose it and select "Always allow plugins for [site name]" to allow Flash playback on the current site by default, or "Run all plugins this time" to allow Flash now but not later.

To play blocked Flash content in Firefox, click anywhere in the gray box where the video would normally appear, or choose the lego-like plug-in icon to the left of the address bar and click either Allow Now or Allow and Remember. To deactivate automatic playback on a site you added to your whitelist previously, click the icon and select Block Plugin.