This song by Guitarra Azul has a very distinctive rhythm that I have also heard in other songs. How is it called? Is it one of the classical flamenco rhythms?
Thanks to guidot for reminding me about this question.
This is a tango. There are a couple different tango rhythms. The most common one (and the one used in this video, played clearly on the upright bass) is tango rhythm 1 in the diagram below:
As seen in the diagram and according to this answer, tango rhythms are characterised by having four beats in a bar and having an emphasis on the "and" of beat two. Both of the rhythms above fit these criteria.
Another point of interest is the 3:2 son clave rhythm being played on the wood claves at 3:18 in the video. The 3:2 and 2:3 rhythms are as follows (2:3 is just 3:2 but the other way round)