This week in social media, former CEO of Twitter Dick Costolo will reportedly be stepping down from his position on Twitter's board of directors. Meanwhile, Snapchat is becoming the newest battlefront for political discussion by design, and Facebook was the true winner of the first GOP debate.

It's time for Social Media Sunday!

Twitter

Costolo to Step Down (even more)?

Late this week, Bloomberg broke the news that Dick Costolo, Twitter's ex-CEO who stepped down from that position earlier this summer but remained on the company's board of directors, plans to vacate the only position he still has at the struggling social media firm.

Citing anonymous sources, Bloomberg reported that Costolo will be out by the end of the year. The beleaguered executive reportedly planned to announce the change to coincide with the appointment of a permanent CEO for Twitter. Co-founder Jack Dorsey currently holds the interim CEO position and hasn't ruled out the possibility of staying at the helm, but Twitter declined to speak on the matter at all.

Facebook

Live Streaming Video Launches, but Only for Celebs

This week, Facebook got into the live streaming video craze that Periscope and Meerkat launched earlier this year. As TechCrunch reported, on Wednesday Facebook launched "Live," a new feature that allows select public figures and celebrities with verified accounts, and thus access to the Facebook Mentions app, to broadcast live video to their followers.

When a celeb starts a broadcast on Mentions, according to Facebook's announcement, a video with the official "Live" tag will be posted on the news feed, where viewers can watch and react with comments, which the celeb can see in real time. Facebook will automatically filter to hide extremely impolite or obscene remarks.

It may seem like jumping on the bandwagon a little late, but Facebook has reportedly been working on the feature since even before launching Mentions in July 2014.

Winning the GOP Debate

The winner of the first Republican presidential primary debate this week is up for, well, debate.

But there's no question Facebook won the social media battle for engagement during the live political event, despite Twitter's typical strength of being the water-cooler in the cloud.

According to analysis by SunTrust, via Barrons, Facebook "dominated the video feed's branding" with its logo displayed on screen throughout the debate, which in part led to over 20 million posts, comments and likes surrounding the event.

Snapchat

Getting Political Ad Filters

Speaking of the GOP debate, Snapchat added a new feature just in time to drum up engagement from its predominantly young userbase: a political ad "filter."

In a small test in Ohio, Snapchat users discovered a new filter to tag their snaps, called "How I Feel About the Bad Iran Deal." The filter is a way to track and encourage discussion on topics, paid for, according to The New York Times, by Secure America Now, a foreign policy advocacy group.

It's not a political statement in itself for Snapchat. For example, in Iowa and New Hampshire, Snapchatters will soon see the first political ad from a left-leaning environmental group.

But it indicates the company is willing to try experimental ad strategies and isn't afraid of selling ads to political causes, even if there's a chance of annoying politically disaffected Snapchat users.