It's worth noting that market share is a relative metric and a number of factors are in play, including a larger overall audience on these services -- viewers watched 1.19 billion hours across the four of them in December, up from 1.06 billion a year earlier. The report suggests that Facebook Gaming's growth is largely due to existing streamers building their audience and new faces drawing big numbers. On average, Facebook Gaming streamers were broadcasting for 63 percent more hours last year than in 2018, which also helped boost viewership numbers.

Twitch is still the biggest player in game streaming by far, at least among Western services. But despite viewing hours growing from 715.6 million to 728 million year-over-year, Twitch's market share dropped from 67.1 to 61 percent. It might be feeling the strain of the competition a bit more these days. The Information this week reported Twitch's ad revenue is not growing as quickly as it hoped.

YouTube Gaming is the second-biggest game streaming service after Twitch, but had almost the same market share as at the end of 2018 (it was up just 0.4 percent to 27.9 percent). That's despite having almost 30 million more viewing hours than a year earlier.

Meanwhile, although it scooped up some big-name streamers from Twitch, Mixer's market share didn't change significantly over the year, according to the report. It went from two to 2.6 percent, even though viewing hours rose from 24.4 million to 31.1 million. Still, it's relatively early days for its star names -- the likes of Tyler "Ninja" Blevins and Michael "Shroud" Grzesiek have been on Mixer for only a few months.

Elsewhere, for the first time in December, a game wasn't the most-viewed category on Twitch. That honor went to Just Chatting, where streamers, oddly enough, hang out and talk with their viewers. StreamElements and Arsenal.gg say viewers watched almost 81 million hours of those streams in December, compared with 74.1 million hours for League of Legends and 58.3 million for Fortnite.

The rise of Just Chatting reflects Twitch's appeal beyond gaming, something it's been striving to bolster over the past few years. That said, it doesn't necessarily mean people are tuning in to watch streamers talk for hours on end. Some of the bigger names, such as Felix "xQc" Lengyel (the most-watched individual Twitch streamer in Q4, per the report) and Tim "TimTheTatman" Betar, often begin their broadcasts by talking with viewers and watching YouTube before hopping into games. Nevertheless, it underscores the fact personalities rather than games are driving streaming viewership, making the battle to lock down talent a major concern for the various services.