Biden introduces himself as ‘Barack Obama’s VP’ despite being the current president (video)

(Crankers) President Joe Biden introduced himself saying this: “My name is Joe Biden. I’m Barack Obama’s Vice President.” Joe Biden is the current president, but he did serve two terms as former President Barack Obama’s vice president as well.
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Much of the commentary about this video revolves around Joe Biden introducing himself correctly. However, as the video shows, Barack Obama is standing to the right of Joe Biden, and Biden is introducing Obama to the audience.
It's likely that Joe Biden was simply being polite or humorous in his introduction, although this video is likely to spark debates about his cognitive and mental fitness.
Did Joe Biden introduce himself as Barack Obama's vice president to be polite or humorous, or did he simply forget he was president?
There's no evidence to suggest or know the answer to that question without the current president, Joe Biden himself, answering that question – if someone ever asks and he responds.
Either way, the social media commentary will carry on and consistently criticize Joe Biden, sparking demands for him to take a cognitive test, as that always seems to be the case when he makes a mental error or appears to make a mistake.