Yeah, the transition process of Yahoo search to show Bing search results has taken a significant step. Around a few days ago Yahoo organic search in USA and Canada has completely sifted to Bing functionalities at the back-end. Currently it has been done for English language only. So if you search in Yahoo US site, you can see “Powered by Bing” message at the bottom of the page.
So if you search Yahoo Web, Image or Video you will get same results as Bing. And it is true for both Desktop and mobile devices.