The jury has lots more power than the system will let on.
If you ever get on on start googling jury rights.

So, the judge can't declare a mistrial if s/he suspects jury nullification? Like in the extreme case presented where jurors ignore DNA and video evidence and just decide to vote not guilty anyway? That's a little scary, especially considering the double-jeopardy rule.

I imagine if you were on a jury, convincing all the other members to nullify would be extremely difficult. It seems much more likely to result in a hung jury except in the most extreme cases (like the slavery and lynching examples provided in the video).

Also, in California at least, jury nullification has itself been "nullified"--judges can remove from the jury any member that indicates they will not give a verdict that corresponds to the facts of law involved in the case.

See: http://cnsnews.com/news/article/california-court-rules-against-jury-nullification

"Do you have any beliefs that might prevent you from making a decision based strictly on the law?"

"As Jury Nulification is within 'the Law', then no, I don't."

The alleged perjury of answering "no" avoided.

One of the downsides of jury nullification not mentioned in the video is that it doesn't afford higher courts the opportunity to correct defects in the law.

In the UK an eleven and a twelve year old boy set fire to some newspapers, which unknown to them spread to a wheelie bin, which spread to another wheelie bin, which spread to a shop and eventually caused ~£1 million damage. They were convicted of arson despite an extremely reluctant jury and even judge, because while it was acknowledged that the boys didn't foresee the risk of the fire spreading the standard of recklessness at the time (which had persisted for around two decades) was an objective one referring to the judgement of a hypothetical reasonable adult.

It took their conviction, and the Court of Appeals upholding that conviction, for the House of Lords to reexamine the bad precedent they'd set in an earlier case and finally revert the standard to a subjective one of the defendant's actual capacity.

It may take thousands of nullifications before legislators even notice that their terrible laws aren't being enforced, while one unsound conviction can make a difference. So your strategy as a juror may be to convict in obviously stupid cases (unconstitutional ones in the US, say), but nullify where the law appears to be functioning as intended but conflicts with your conscience.

Yes, but the upside is that a defendant is not required to shoulder the burden of appealing (multiple) 'wrong' or 'defective' convictions in order to hope to force the slow to move legislature to consider correcting their mistakes. That seems completely unfair to me.