A bullet button is a device used to permanently fix a magazine in a semiautomatic rifle that was originally built to accept a detachable magazine in order to comply with gun laws in California. It replaces the magazine release with a block and the user needs to remove the magazine by using a tool.
The intent of the law requiring the bullet button was to allow AR (and other semi) owners to keep their rifle, legally, by DISABLING the ability to quickly and easily change magazines. Essentially it makes the detachable magazine a FIXED magazine. The mag can still be removed, but requires a tool (the fmj bullet of a standard 5.56mm round will work, just as it works to adjust the M16 sights, hence the name "bullet button") and is a disassembly process NOT a reloading process.
I think this point should have been made clear, and I think the entire delivery would have been better without the paranoid redneck patios, but that's just my opinion.
Also and ironically, the talking head on the news actually was correct, (but only in one sentence), but not in his overall point.
He said "disabling the bullet button turns your legal semi into an illegal assault weapon" That is technically correct in CA. ALL the rest of what he said was bovine excrement.
Disabling the "bullet button" DOES make your CA legal AR into an "illegal assault weapon". Illegal because it breaks CA law, and "assault weapon" because the term "assault weapon" is defined in CA law as SEMIAUTOMATIC firearms with certain features (one of them is a detatachable magazine).
Disabling the bullet button does NOT make the rifle full auto. No WAY in Hell. ALL disabling that bullet button does is break CA law by returning the gun to the way it was originally designed to operate, regarding a detachable magazine. It affects NOTHING else.
ALSO (and not mentioned) under CA law, mags can only hold 10 (ten) rounds, and larger size mags must be physically blocked so they cannot hold more than the lawful amount.