Ive noticed this problem yesterday. I was on a video hosting website and while videos alone seemed fine, when I started watching a video in a playlist I noticed the sound is playing multiple times.
Today I noticed on 9GAG that when I open a post in separate tab, the video, even paused, starts playing it's sound whenever I press spacebar. What I mean is, if Im typing out a comment, every time I add a space, the sound from video starts playing, but they all stack, so I have multiple sounds playing at the same time.
Additionally, after bringing my laptop from sleep mode (not something that caused the previous problems) a video from yesterday started randomly playing.
Does anyone know what could be causing this?