Apparently that guy is not actually a white belt. Here is the explanation given in one of the comments:
Veselin Dukov is not a beginner, he's actually a very advanced grappler, but he is technically a white belt because he has less than 10 sessions with the Gi. The black belt shoudn't be ashamed because he lost to a young and very talented grappler who has won the Bulgarian championships on various occasions and ended up second in the Euro ADCC trials. What happened at the tournament was, that he did the Expert No Gi, and wanted to test his skills against black belts in the Gi. Since he's not a black belt, he obviously doesn't have one and he borrowed a white belt from a female competitor. We asked NAGA officials if he could use a white belt and they said OK. So don't give the BB such a rough time, he was legit.
