Hi, and welcome to FineTunedMac. smile

Please be more specific...
  1. At what point do you see that error message... During/after d/l, when you try to open the .dmg file, some other time?
  2. Please post the text of the error message verbatim and tell us which app/utility is generating it.
  3. Exactly which MacBook are you running?
  4. Which version of OS X are you running?
  5. Which version of VLC are you trying to d/l and from where?

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In Memory of Harv: Those who can make you believe absurdities can make you commit atrocities. ~Voltaire