The used voice is definitely not Flemish. A rolling r is supposed to be made by the tip of the tongue vibrating rapidly due to the airflow. A French r in contrast, is a guttoral sound made with the back of the tongue, and sounds significantly different. The proper way to say an r in Dutch is to use the rolling r, but that's difficult to learn if you haven't been doing it from childhood. In that case, the French r is a good enough substitute; in fact, in Ghent the French r is native to the dialect and used by most people.
The British sound that is used for the letter r and which is made with the tongue against the top of the mouth and which is almost a vowel is definitely not the right sound though
There are several ways the r can be pronounced in Dutch depending on the region: https://nl.wikipedia.org/wiki/Uitspraak_van_de_r_in_het_Nederlands
Hencethere is no "proper way" to pronounce the r in Dutch.