I guess thatr the Tamron wins hands down for video use over the canon mk2 due to the VC?
Only if you use handheld static video, but for most professional applications a body stabilization gear is used which prevents the typical IS/VC "skip" when moving around.
When handheld the VC is better than my Canon 70-200 f/2.8 L IS II ... but once you set it on a tripod and shoot, Canon lenses produce superior clarity, sharpness & colors. The 24-70 f/2.8 VC is a great lens for its price - basically value for money. But if you want tack sharp image across the image, get Canon 24-70 f/2.8 L II
5D MK III, 16-35/2.8 L II, 24-70/2.8 VC, 24-105/4 L IS, 70-200/2.8 L IS II, 100/2.8 L IS, 40/2.8, 50/1.4, 85/1.8, 150-500 OS, 600EX-RTx2, ST-E3-RT, Rokinon 24/3.5 T-S, D7100+18-300 VR, YN568EX, 055CXPRO4+468MGRC2, 190CXPRO4+322RC2, Gorillapod Focus+496RC2, CamRanger, B+W filters, Konova K3/31.5 etc