Here’s some more info from the comments section on reddit
Never thought I’d ever be Googling “Obama boner video”, but I was able to find this. Apparently, it’s from May 8th, 2008, after the NC primary. https://obambi.wordpress.com/2008/05/27/obama-gets-a-boner-and-does-the-donkey-show-for-the-media/
Says this video does not exist
Direct link to video https://www.youtube.com/watch?v=04RhsO_fyZQ