You can find more details about the series and its episodes on the official ITV page or via the Beowulf: Return to the Shieldlands IMDb page.
The "X..." typically precedes a video codec like XviD or x264 , which indicates how the video was compressed. Beowulf.Return.to.the.Shieldlands.S01E05.HDTV.X...
In this specific episode, the plot follows Beowulf as he travels to the Mere to build an alliance with the Chancellor, only to find himself caught in a web of secrets and a brewing conflict between tribes. You can find more details about the series