title_body: How to prevent a 5V supply from sagging to 4.6V when the FPV camera is on?
upvoted_answer: I've pulled a few specs together from the parts you linked to:
  
  
  Flight controller:
  
  
  Input: 2S to 6S LiPo (7V to 20V)
  Output: 5V 3A
  
  VTX:
  
  
  Input: 7V to 24V
  Output: 5V 0.3A
  
  Camera:
  
  
  Input: 5V 0.65A  --OR-- 12V 0.27A
  
  
  
  You don't mention what size battery you are using, but I will assume it is in the FCs range of 2S to 6S.
  
  
  The camera needs too much current (0.65A) to get it's 5V from the VTX (max 0.3A)
  The VTX should be connected to the battery
  The FC should be connected to the battery
  The camera should be connected to the FC 5V supply
  
  
  This wiring should work, if you have no other large 5V loads connected to the FC.
  
      ╔══════════════════╗  ╭───────╮
      ║ LiPo Battery     ╟──┤ 7-20V ├────┬──────────┐
      ╚══════════════════╝  ╰───────╯╔═══╧═══╗  ╔═══╧═══╗  ╭────╮
                                     ║  VTX  ║  ║  FC   ╟──┤ 5V ├────┐
                                     ╚═══════╝  ╚═══════╝  ╰────╯╔═══╧═══╗
                                                                 ║  Cam  ║
                                                                 ╚═══════╝
  
  
  Alternatively you will need a separate DC-DC converter or regulator to supply the 5V. A capacitor is great for smoothing out surges in demand, but won't hold up the 5V rail if the load is constantly too large.