strobe effect in final cut pro
 

not sure if it is actually called strobing, but where you rapidly cut from one video source to the other every couple of frames. can anyone advise me the best way to do this?

The one you want is called "Blink" (Effects > Video Filters > Video > Blink) ... place one clip above the other on your timeline, then add the Blink filter to the upper layer, adjust the filter's parameters as required

Check out Luca's excellent (and free) variations of this filters too: dual flicker plugin
lucas_flash_transition
lucas_flicker_wipe_transition