Is this new? http://imgur.com/JIria.png
PS: clicking the "play" icon directs you to the linked page and do not play the video inside the SERP (what I expected)
PS2: the video "How to make an impact flash bomb" has absolutely nothing to do with my query [keyboard shortcuts transmission mac].

I've never seen that before.

Perhaps something new too, the "also try" section in the right bar instead of ads
http://www.google.com/search?hl=en&q=how+to+say+I+love+you

Never seen both, play icons are the same as used when showing the music onebox.

i have seen it maybe 3 weeks ago
the icon is part of the nav file, which wasn't changed since google launched new design:
http://www.google.com/images/srpr/nav_logo13.png

I have not come across this before. Perhaps a way of getting more video into search with disrupting eye tracking etc – or maybe from distracting from the Adwords clicks?!

Click 'show more results' for wonderhowto.com results and they have lots of video indexed this way. Interesting that they are all hosted on their site and not YT.

A quick search for more 'How to' search results didn't find any more websites with these video icons.