Close every tap except one.
Delete your history and cookies.
Close and restart the browser.
The reason you keep getting Obama videos is because you click on Obama videos and youtube believes you want to watch Obama videos.
If you're logging on to youtube and clicking on Obama videos your search history is likely set in stone.
I rarely log in to youtube with my user name. When I do, my past history comes back to haunt me because youtube links me to my past video choices.
Don't log in with your user name unless you want to comments and clear your history and you likely won't get Obama videos.
I don't click on Obama videos so I don't get recommendations for Obama videos.
Logging out and clearing your history will save you a lot of aggravation.
Clear your history and go back to youtube. If you don't log on you'll find the Obama videos are gone.
I clear out youtube history often.....keeps me sane!