I see it didn't happen with win7 but does with win8. Weird, but my spidey sense tells me it has something to do with the VGA only monitor or the adapter. All 3 of my monitors are digital and there's nothing like that happening. Your vid mentions this is a 5850 and I have the 5870 so..
So, can you beg, borrow, buy a digital monitor to replace the old vga.. just for testing purposes?
#1: Phenom II C2 955BE @ 3.6, Antec Kuhler 920, Gigabyte GA-MA790FX-DS5, Asus 5870/V2, ASUS Xonar D2X, 4 x 1gig OCZ2N1066SR2GK @800, Antec Truepower New 750, Arc Midi, Vistax64
#2: MSI A88X-G45, AMD A10-7850K, IGP, AMD 2x4GB 2133 (R938G2130UK), Antec 750 True, 128GB Sandisk SSD, WD Black 1TB, Win8.1pro x64
#3: Athlon 64 X2 4200+, AGP 1950pro, Audigy 2, Asus A8V-D, 2gig ram, Enermax 465P, Antec900case. Now on Win8.1pro cat 10.2