That capture card records to an external HD. So you would:
1. Record on PC A via the external card to the external HD
2. When done, you would disconnect the HD from PCA and connect it to PC B
I don't see how this is any different than just having the file transferred over an ethernet cable, except this way no playing with cable connects / disconnects.
The reason I imagine that the video guy / gal was doing this I imagine is:
A. If he's using 1 or 2 GFX cards, gaming performance would be better on a Z97 based system
B. For video editing, depending on the app, performance would be better on an X99 based system