Google's John Mueller said in the webmaster hangout from Friday at the 21:52 mark that Google tends to launch many new changes to the search engine, including algorithm updates and tweaks, towards the end of the quarter.
This answer was in response to seeing a video ranking change around when Penguin launched. He said, he isn't sure but Penguin has nothing to do with the video search results, so it is probably just a coincidence and Google does like to launch and complete things before the end of each quarter.
He said:
Towards the end of the quarter is usually a time where I see a lot of Google teams say, oh we always wanted to launch this so therefore will try to launch it at least by the end of the quarter so with that we can say we be completed at this quarter. And you'll see a lot of different things launching during during a time like that.
Here is the video embed:
So maybe there was a Google video search algorithm update too a few weeks ago?
Forum discussion at Google+.
This post was scheduled to go live today but was written earlier - I am currently offline today.
