So I looked in the Console for around the time when the video blink happened and here is what I have:
2012-10-27 7:58:26.425 PM WindowServer[87]: Received display connect changed for display 0x3f003c
2012-10-27 7:58:26.426 PM WindowServer[87]: Received display connect changed for display 0x3f003d
2012-10-27 7:58:26.426 PM WindowServer[87]: Received display connect changed for display 0x2b343212
2012-10-27 7:58:26.429 PM WindowServer[87]: No display devices are on-line. Switching to virtual display mode
2012-10-27 7:58:27.507 PM WindowServer[87]: Received display connect changed for display 0x3f003c
2012-10-27 7:58:27.507 PM WindowServer[87]: Received display connect changed for display 0x3f003d
2012-10-27 7:58:27.507 PM WindowServer[87]: Received display connect changed for display 0x3f003e
2012-10-27 7:58:27.520 PM WindowServer[87]: New display device coming on-line. Switching from virtual display mode
2012-10-27 7:58:27.524 PM WindowServer[87]: Created shield window 0x110 for display 0x2b343212
2012-10-27 7:58:27.524 PM WindowServer[87]: handle_will_sleep_auth_and_shield_windows: no action for lock state 1
2012-10-27 7:58:27.799 PM WindowServer[87]: MPServiceForDisplayDevice: Invalid device alias (0)
2012-10-27 7:58:27.800 PM WindowServer[87]: Display 0x003f003c: GL mask 0x1; bounds (3072, 0)[1 x 1], 1 modes available
off-line, enabled, Vendor ffffffff, Model ffffffff, S/N ffffffff, Unit 0, Rotation 0
UUID 0xffffffffffffffffffffffff003f003c
2012-10-27 7:58:27.800 PM WindowServer[87]: Display 0x003f003d: GL mask 0x2; bounds (3073, 0)[1 x 1], 1 modes available
off-line, enabled, Vendor ffffffff, Model ffffffff, S/N ffffffff, Unit 1, Rotation 0
UUID 0xffffffffffffffffffffffff003f003d
2012-10-27 7:58:27.800 PM WindowServer[87]: Display 0x2b343212: GL mask 0x4; bounds (0, 0)[2048 x 1152], 18 modes available
Main, Active, on-line, enabled, boot, OpenGL-accel, Vendor 10ac, Model d01d, S/N 304e3553, Unit 2, Rotation 0
UUID 0x000010ac0000d01d304e355300000000, ColorProfile { 3, "HD 709-A Calibrated"}
2012-10-27 7:58:27.800 PM WindowServer[87]: GLCompositor: GL renderer id 0x01024400, GL mask 0x00000007, accelerator 0x00003243, unit 0, caps QEX|QGL|MIPMAP, vram 580 MB
texture units 8, texture max 16384, viewport max {16384, 16384}, extensions FPRG|NPOT|GLSL|FLOAT
2012-10-27 7:58:28.110 PM WindowServer[87]: Created shield window 0x111 for display 0x003f003c
2012-10-27 7:58:28.111 PM WindowServer[87]: Created shield window 0x112 for display 0x003f003d
2012-10-27 7:58:28.125 PM WindowServer[87]: Created shield window 0x113 for display 0x2b343212
2012-10-27 7:58:28.126 PM WindowServer[87]: Display 0x2b343212: MappedDisplay Unit 2: Startup Mode 2048 x 1152, CGSThirtytwoBitColor, Resolution 1, IOMode 0x80001000, IODepth 0x0, IOReturn 0x0
2012-10-27 7:58:28.126 PM WindowServer[87]: Display added
2012-10-27 7:58:28.126 PM WindowServer[87]: Display removed
2012-10-27 7:58:28.128 PM WindowServer[87]: Display 0x2b343212: GL mask 0x4; bounds (0, 0)[2048 x 1152], 18 modes available
Main, Active, on-line, enabled, boot, OpenGL-accel, Vendor 10ac, Model d01d, S/N 304e3553, Unit 2, Rotation 0
UUID 0x000010ac0000d01d304e355300000000, ColorProfile { 3, "HD 709-A Calibrated"}
2012-10-27 7:58:28.128 PM WindowServer[87]: GLCompositor: GL renderer id 0x01024400, GL mask 0x00000007, accelerator 0x00003243, unit 0, caps QEX|QGL|MIPMAP, vram 580 MB
texture units 8, texture max 16384, viewport max {16384, 16384}, extensions FPRG|NPOT|GLSL|FLOAT
2012-10-27 7:58:28.128 PM WindowServer[87]: Display 0x003f003c: GL mask 0x1; bounds (3072, 0)[1 x 1], 1 modes available
off-line, enabled, Vendor ffffffff, Model ffffffff, S/N ffffffff, Unit 0, Rotation 0
UUID 0xffffffffffffffffffffffff003f003c
2012-10-27 7:58:28.128 PM WindowServer[87]: Display 0x003f003d: GL mask 0x2; bounds (3073, 0)[1 x 1], 1 modes available
off-line, enabled, Vendor ffffffff, Model ffffffff, S/N ffffffff, Unit 1, Rotation 0
UUID 0xffffffffffffffffffffffff003f003d
2012-10-27 7:58:28.150 PM WindowServer[87]: MPAccessSurfaceForDisplayDevice: Set up page flip mode on display 0x2b343212 device: 0x1084c2320 isBackBuffered: 1 numComp: 3 numDisp: 3
2012-10-27 7:58:29.532 PM WindowServer[87]: **DMPROXY** (2) Found `/System/Library/CoreServices/DMProxy'.
2012-10-27 7:58:29.642 PM WindowServer[87]: Display 0x2b343212: MappedDisplay Unit 2; ColorProfile { 3, "HD 709-A Calibrated"}; TransferFormula (1.725494, 1.725494, 1.725494)
2012-10-27 7:58:29.656 PM WindowServer[87]: Display 0x2b343212: MappedDisplay Unit 2; ColorProfile { 3, "HD 709-A Calibrated"}; TransferFormula (1.725494, 1.725494, 1.725494)
2012-10-27 7:58:30.126 PM WindowServer[87]: **DMPROXY** (2) Found `/System/Library/CoreServices/DMProxy'.
2012-10-27 7:58:30.151 PM WindowServer[87]: Display 0x2b343212: MappedDisplay Unit 2; ColorProfile { 3, "HD 709-A Calibrated"}; TransferFormula (1.725494, 1.725494, 1.725494)
2012-10-27 7:58:30.164 PM WindowServer[87]: Display 0x2b343212: MappedDisplay Unit 2; ColorProfile { 3, "HD 709-A Calibrated"}; TransferFormula (1.725494, 1.725494, 1.725494)