I suppose that makes sense given that information is encoded as a series of key frames interspersed by 'I-frames" that simply encode the delta to the previous key-frame when using most compressed video algorithms. So cutting in-between key-frames doesn’t really make sense since the I-frame would no longer have anything to reference it’s delta to.
I know it may seem obvious, but did you check the pins of the BOOT0 switch itself and the nearby capacitor? A stray bit of solder there could cause the switch to appear always held down by shorting either the cap or the switch. It doesn’t appear that the boot0 line goes anywhere other than there and the main microcontroller so the issue is likely there.
LosslessCut, the Swiss army knife for lossless video and audio editing (ubunlog.com)
Blackpill microcontroller always in Boodloader mode
I am not sure where to ask this, so here it goes:...