I can't see the video, don't have QT 7 here. But I'll take a SWAG (super wild a**ed guess) anyway... your lighting may be at fault. Many outside nighttime lights are gas discharge types and these emit light in pulses at twice the power line frequency. Your camera's effective shutter rate will be very nearly, but not quite, synchronized with a multiple of this. In the USA, it's 60Hz and we have a camera field rate of 59.94/sec (interlacing) for a frame rate of 29.97/sec. In the UK it's 50Hz and 24.98fps. If this is the case, you'll see a dimming and brightening occuring in slow cycles that I roughly estimate to be about 40 second long. There isn't much you can do about this except provide incandescent lighting which has a much more constant output.
Fav quote - "Experience is whatcha don't get 'till ya don't need it no more."
System - Athlon 1.4GHz, Win98, Hauppauge PVR250 receiver and compressor.
Software -Magix Movie Edit Pro 10, Nero 6 + NeroVision Express, Moho 4.61, PSP 8.1, Bryce, Quicktime 6.52 pro, Goldwave 5, DVD-Lab.
Cameras - Panasonic GS9, Canon ES8400V, Canon EOS D20 and Canon A70