Perhaps I should have been clearer. When I meant "secure" I did not mean cryptographically secure but instead secure in that data was actually removed. This generally requires special, SSD (or NAND, rather) aware tools that explicitly erase each block.

Running the OS X "secure erase" tool will do nothing but wear the eMMC further and make disk performance worse.

The camera not recording smoothly likely has more to do with the CPU getting interrupted by something else. Of course, now that you've smashed your internal memory several times over then chances are your recording will be worse now.