I also use the video mixing allot using version Cross 3.4.2 and the U-Mix Control Pro controller and it works great.
I recently upgraded to Cross DJ Pro 4.0.0 and the new interface is still very confusing to me, especially when it comes to the video mixing. Cross DJ Pro 4.0.0 (32 bits) crashes about every 10 to 20 minutes with or without video enabled, so its hard to get used to the new interface and also to explore features, and then get used to it.
I have reverted back to Cross 3.4.2 for now.