I'm glad to hear that the others didn't experience this repeatedly.
Here are the details:
First the top right corner square had an add with video and audio start. I did not click on any thing, but I suppose there was the off chance that the cursor rolled over the area. It was not an ad that I had seen or heard when I was surfing the web on other sites. I clicked on the x in the top right corner and it stopped.
A minute later a video started playing in the same spot. It had a youtube logo in the lower right corner of the the square. There was no x in the top right corner, so I actually closed the tab and it stopped.
I open a tab and went back to my profile. This time the audio came on automatically, but the video did not match any where. I checked some other tabs to see if they were the source, but no. I closed the tab again and it stopped.
I opened the tab again. I got some audio automatically again, and I noticed that the ad strip at the very top right was blurred as if it was a section of a stopped video. The Venus razor jingle was playing. I closed the tab and opened it again. Some other audio played so I hit mute on my lap top and reported it and closed the tab and turned my audio back on.
Four hours later I return write this - It hasn't happened again even though I haven't turned off my computer in the mean time.