I've heard the same thing, that pertains mostly to black male defendants. Any such bias may not be a problem in this case. The commentator did mention that all the OTHER jurors (except the grandmother) didn't take their eyes off Ashton while he was speaking.
I’ve served 3 times on jury duty (doesn’t exactly make me an expert, does it?!) and we always had one black male jury member. They always wanted to go for acquittal no matter what the race of the defendant. Sometimes this is good because it makes other jurors put on their thinking caps and work out the truth. On the other hand, it can be really trying!