Of the many amazing features in Google Plus, one is the option of directly searching(and watching) YouTube videos without logging-out of Google Plus profile.
Its possible due to the inbuilt YouTube search option provided with Google Plus.
You must have noticed the YouTube button on left side of right side of your G+ profile. To search a video, hit the button and you’ll see a search box sliding out.
Then enter your video name/search query. A pop-up window would open up with a video starting to play. Usually its the best matching video or a similar video that you watched previously. A playlist would also generate automatically for the entered search query.
Here is how I’ve used the feature,