If there is a power sequencing or similar issue on startup, the RPi GPU may not detect the PiCapture board as the camera. This will not be evident until you try to do a capture. At that point, since there is no camera detected, an error will result. Note that once this error occurs it requires a complete power cycle to correct it because the GPU error recovery doesn’t work properly.
I suggest that you remove the extra capacitance you have added and try a standard RPi 2.5A power supply. Note that standard RPi power supplies are 5.3V – 5.5V and are current limited.
Al Testani
Lintest Systems