This guy says here there are two ways of "making the /r/ sound". His explanation lacks academic rigor and necessary phonetic details. He claims the first way is: "It's like a /l/, with your tongue against the roof of your mouth. Tongue up, behind front teeth; lips relaxed." And the other way: "It's like a /v/, with your top teeth near your bottom lip. Tongue relaxed; top teeth against lower lip."
I tried but failed to reproduce the sounds he describes. I don't think my /r/ is either of those. (U.S. West Coast parents. Raised overseas. Most of my adult years have been spent on the East Coast)
I was under the impression that /r/ is effected most commonly as the voiced postalveolar approximant on either side of the pond. But what that guy describes doesn't seem to fit. So what are the two phones (sounds) in phonetics that he is likely referring to?
Even mispronunciations are phones too. If I point to an incorrect solution to an arithmetic problem and ask "what's the number presented in the solution?" The result may well be a miscalculation, but it is still a number.
If you watch the video, the YouTuber claims that /v/ sound has become the more popular realization of /r/ in the UK.