UNDATED (CNN) -- As part of its latest transparency report Google revealed that last year it removed some 640 terrorist videos from YouTube after a request from British law enforcement. But is taking those videos down an effective way to stop terror propaganda?

From the new head of Al Qaeda core Ayman al Zawahiri to terror propagandist Ayman al Awlaki, using the internet to spread the jihadist message is a tool of the trade for terrorists.

Google agreed to remove some 640 terrorist videos from YouTube at the request of law enforcement officials in the UK.

There's been a myriad of propaganda and do-it-yourself terror tricks posted in the form of videos. The problem with trying to take some of the more egregious material off the Internet is that it has a way of popping right back up again. Aaron Zelin with the Washington Institute for Near East Policy says, "In a sense a whack a mole type of thing where especially activists in the west create 20 or 30 YouTube accounts and they primarily use one and then if somebody flags it they just take it down and go to the next one. So it's sort of this cat and mouse game that you're playing. Google, which is a parent company to YouTube, does have a policy for dealing with terrorist content online."

Their "Community Guidelines prohibit dangerous or illegal activities such as bomb making, hate speech, and incitement to commit violent acts."

With literally hundreds of videos being posted by some Jihadi groups, getting a handle on all of the terrorist information that's out there can be a challenge.

But this is the best defense so far: a built-in flagging mechanism that alerts Google moderators to take a closer look.

Google says the flags are taken seriously and that they are constantly monitored. Again, in a statement, Google said: "our review teams respond to flagged videos around the clock, routinely removing material under those guidelines when content is flagged by users or other external groups."

but some experts say there can be hidden benefits to keeping some of this material online. Brian Fishman with the New America Foundation says, "One of the values of these videos being out there, we can sort of understand what our enemies are thinking about or what these kinds of folks are thinking about."

Here in the U.S. The government, according to Google, made 1,759 requests for content to be removed from YouTube between July and December of last year. Of those requests, only one removal was in the name of national security.