This was for a video that was supposed to air during the 2012 Republican convention. It's not new. https://www.washingtonpost.com/news/the-fix/wp/2015/11/06/2012-was-closer-to-being-the-year-of-trump-than-you-might-remember/ https://twitter.com/Pervaizistan/status/1302427987929899008

Here's the video. This was a subplot in 2012 that was pretty well known, but since Trump was just Trump-the-TV-guy at the time, it's understandable that people missed it.

I haven't read Cohen's book, but either he or the person who tweeted the summary above clearly misrepresents a scenario in which Trump was trying to get attention by applying his "Apprentice" shtick to Obama.

For those skeptical that it was widely covered, the video apparently aired on the Today show, per this contemporaneous article. https://www.washingtonpost.com/blogs/post-partisan/post/the-donalds-video-should-have-trumped-eastwood/2012/09/18/28c315c6-01df-11e2-9367-4e1bafb958db_blog.html